A simulated quantum stress test conducted using OpenAI’s ChatGPT o3 model has raised fresh concerns about the future of digital assets. The simulation explores a hypothetical breakthrough in quantum computing by 2026 that would render many of today’s cryptographic standards obsolete, potentially leading to widespread collapse across the cryptocurrency ecosystem. Quantum computers use qubits, which can exist in multiple states at once due to the principles of superposition and entanglement. This allows them to perform complex calculations at speeds far beyond what is possible with classical machines. According to o3, a sudden leap in quantum capability, such as the development of a 10,000-qubit fault-tolerant machine with sufficiently low error rates, could break the security systems underpinning major blockchains like Bitcoin and Ethereum. ChatGPT o3 Warns of ‘Q-Day’ Extinction Risk for Blockchains o3 raised red flags across the crypto industry, warning that the rise of quantum computing—referred to as “Q-Day”—could pose an extinction-level threat to major blockchains. At the heart of blockchain security lies the asymmetric cryptography model: private keys generate public keys , but not the other way around. This one-way function is what secures digital wallets and signs transactions. Quantum computers might sound like another buzzword in the tech world, yet their threat to #cryptocurrency is very real and approaching fast. Scientists may differ on the timeline, but they all agree: “Q-day” is not a matter of if, but when. #Bitcoin https://t.co/SdH4NiTMoo — Cryptonews.com (@cryptonews) June 13, 2024 Quantum computing breaks this assumption. Using algorithms like Peter Shor’s , proven in theory to efficiently factor large numbers, quantum systems could reverse-engineer private keys from public data. “A chain is only as secure as its signatures,” the model warns. “Once signatures break, the chain breaks.” The o3 model stress-tested major blockchain protocols under a Q-Day scenario in which quantum machines can break cryptographic standards like ECDSA and RSA. The findings are sobering. Bitcoin: Legacy Risk and No Governance Pathway Bitcoin, which still uses the Elliptic Curve Digital Signature Algorithm ( ECDSA ), was flagged as particularly vulnerable. As noted by o3, a significant portion of BTC remains locked in legacy wallets with no quantum-resistant protections. A 2020 Deloitte study further estimated that up to 25% of Bitcoin holdings could be compromised, especially coins stored in exposed or reused addresses. Data from Project Eleven reinforces this concern: over 6.2 million BTC, worth approximately $648 billion, are stored in addresses with exposed public keys. This translates to more than 10 million wallets that could be at risk once quantum computers achieve sufficient decryption power. 🚀 @Tether_to CEO @paoloardoino has warned that quantum computing could eventually pose a threat to inactive Bitcoin wallets. #Bitcoin #Quantum https://t.co/u8DCYrTjYw — Cryptonews.com (@cryptonews) February 9, 2025 The problem is compounded by Bitcoin’s structural rigidity. What has long been praised as Bitcoin’s strength , its conservative dev culture and emphasis on protocol stability, now poses a liability. In a crisis, Bitcoin’s inability to adapt quickly could delay vital countermeasures. As OpenAI’s o3 model puts it, “Bitcoin’s survival isn’t cryptographic—it’s sociopolitical. Without preemptive upgrades, post-Q-Day drains will begin within days of the breakthrough.” While discussions around post-quantum signature schemes like XMSS or Dilithium have occurred within Bitcoin Core, no concrete implementation or accepted BIP exists. The introduction of lattice-based alternatives (e.g., Falcon) remains theoretical, with no set roadmap. According to o3, Bitcoin network survival would likely depend on one of two strategies: A politically contentious fork to a quantum-safe Bitcoin variant A preemptive key rotation or shielding mechanism that avoids exposed legacy keys Ethereum: More Adaptable, But Still At Risk While Ethereum shares Bitcoin’s cryptographic vulnerability, relying on the ECDSA, it ranks significantly higher in adaptability. The o3 model flagged Ethereum’s active developer community, rapid upgrade history, and flexible governance as key assets in navigating a post-quantum scenario. Unlike Bitcoin, Ethereum has demonstrated the capacity to coordinate complex transitions. The DAO fork, Ethereum 2.0 Merge , and the Shapella upgrade all serve as precedent for community-driven protocol evolution. “Ethereum can adapt,” o3 concluded, “but only if it moves quickly.” Still, the shift to post-quantum cryptography would require extensive infrastructure overhauls. These include wallet standards, signature validation rules in smart contracts, Layer-2 rollups, and developer tooling. Many of these components were built on cryptographic assumptions that would not hold after a quantum breakthrough. Account abstraction is only half-done The end goal is non-ECDSA accounts (multisigs, key changes, quantum-resistant, privacy protocols (!!)) being true first class citizens A lot of good work recently on aggressively simplifying 7701 to make this happen https://t.co/j66geDAoC8 — vitalik.eth (@VitalikButerin) April 27, 2025 The o3 model simulation emphasized this point, saying, “Ethereum is the only major L1 chain with a plausible fast-track governance protocol for quantum threats. But most dApps on Ethereum aren’t ready.” However, Ethereum’s programmability, a defining strength, also creates a unique risk surface. Millions of deployed smart contracts, including financial primitives on protocols like Uniswap, Aave, and MakerDAO, use static cryptographic calls vulnerable to quantum decryption. Many are immutable and cannot be patched after deployment. That said, proxy patterns and upgradeable architectures like OpenZeppelin’s implementation give some contracts a pathway for modification. But these only apply where foresight was used. Vast portions of Ethereum’s contract base may be impossible to rescue post-Q-Day without chain-wide intervention. For Ethereum to remain viable in a post-Q-Day world, o3 noted the following actions will be necessary: Roll out hybrid cryptographic wallets supporting post-quantum signature layers (e.g., Falcon, Dilithium). Incentivize or mandate critical dApps to adopt quantum-safe signature schemes in proxy contracts. Leverage Layer-2s for isolated asset migration and transaction validation under new cryptographic rules. Coordinate a network-wide “key rotation” event with community buy-in, governance clarity, and tooling support. Other Chains and DeFi: Varying Levels of Readiness Algorand: Purpose-Built for the Quantum Era Among all the Layer-1 chains o3 analyzed, Algorand emerged as one of the most quantum-resilient. Designed with future-proofing in mind, the protocol already incorporates cryptographic innovations such as Verifiable Random Functions (VRFs), and it has actively explored lattice-based encryption methods like NTRU, a class of cryptography believed to be quantum-resistant. “If Q-Day hits in 2026,” the o3 model observed, “Algorand is one of the only chains with a 12-month adaptation head start.” Algorand’s pipelined Byzantine Fault Tolerant (BFT) consensus rotates validator keys regularly, reducing the exposure window of any single cryptographic signature. More on Algorand's post-quantum technology: https://t.co/NIQEnbER0P — Algorand Foundation (@AlgoFoundation) May 27, 2025 According to o3, its structured governance and fast finality also enhance its ability to implement protocol-level upgrades quickly in the face of emerging threats. Polkadot: Modular Agility Meets Cryptographic Risk Polkadot ranked just behind Algorand in terms of readiness. The network’s parachain architecture allows semi-independent blockchains to run in parallel, each potentially adopting its own quantum-resilient cryptography without waiting for a full network-wide consensus. According to o3, this modularity offers developers the freedom to implement post-quantum upgrades on a per-parachain basis. However, Polkadot currently relies on Schnorr-based BLS signatures , which are vulnerable to quantum attacks. Still, its OpenGov system and decentralized treasury could support rapid upgrade cycles when needed. Cardano: Academic Rigor, Operational Drag Cardano presents a paradox. It is one of the few blockchain platforms deeply invested in the academic exploration of post-quantum cryptographic techniques, including both lattice- and hash-based signature schemes. o3 noted that Cardano’s extended UTXO model also provides a more modular smart contract framework, which may ease the migration to new cryptographic primitives. Post-Quantum Cardano https://t.co/MpNWSo8KWm — Charles Hoskinson (@IOHK_Charles) February 20, 2025 However, Cardano still relies on Ed25519 signatures, which are quantum-susceptible, according to o3. And while its Voltaire governance phase is intended to support decentralized decision-making for protocol upgrades, it remains under development. As the o3 model put it, “If crypto were judged on whitepapers alone, Cardano would thrive. But Q-Day doesn’t wait for peer review.” Privacy Coins: From Anonymity to Liability Privacy-focused cryptocurrencies like Monero and Zcash face a uniquely grim outlook. Their core innovations of ring signatures, stealth addresses, and zero-knowledge proofs offer strong protections against classical decryption but may provide little defense against quantum attacks. o3 noted that quantum algorithms capable of breaking elliptic curve cryptography could dismantle the projects’ anonymity features, exposing past transactions and rendering current privacy guarantees moot. Compounding the threat is the pseudonymous governance model, which makes coordinated upgrades or overhauls difficult. “Quantum computing doesn’t just de-anonymize Monero,” the o3 warned, “it breaks its reason to exist. Privacy becomes exposure.” DeFi Protocols: Collateral Damage from Layer-1 Failures Decentralized finance (DeFi) protocols, particularly those built atop Ethereum such as Aave, Compound, and MakerDAO, face second-order vulnerabilities. While these protocols do not directly implement ECDSA at their core, they depend entirely on Ethereum’s base-layer security. If Ethereum’s signature scheme were compromised and Layer-1 wallets became exposed, the smart contracts securing billions in TVL (Total Value Locked) would be undermined; regardless of whether the dApps themselves were quantum-aware. o3 summarized the cascading risk simply: “If the base layer fails, so does the application.” Compounding the issue is the immutability of many smart contracts. While some DeFi platforms use proxy architectures for upgrades, many early deployments do not, making them inflexible in crisis scenarios. Meme Coins and High-Beta Tokens: Virtually Defenseless At the other end of the spectrum lie meme coins and low-infrastructure tokens, which the o3 model described as “nearly defenseless.” These tokens typically lack development teams, formal governance mechanisms, or upgrade paths, leaving them acutely vulnerable to any sudden shifts in cryptographic assumptions. In the event of Q-Day, such tokens would likely suffer immediate liquidity shocks, with whales offloading positions to avoid permanent loss. The community might attempt to fork the project onto a new chain, but without technical leadership, meaningful migration is unlikely. Who Is Ready for Q-Day? The o3 simulation’s sector-by-sector stress test does not predict which coins will succeed in market terms, but rather which systems have the structural capacity to survive a game-changing leap in computational power. Based on cryptographic architecture, governance agility, and ongoing research, the post-quantum readiness landscape looks like this: Best Positioned Today Apart from Algorand , Polkadot , Ethereum, and Cardano mentioned above, these other coins have been noted to be well positioned in the case of a Q-day. Cosmos Ecosystem (ATOM, Juno, Osmosis) Cosmos shares Polkadot’s modular philosophy. Independent zones (chains) communicate through IBC (Inter-Blockchain Communication), allowing sovereign upgrades. Projects like Juno and Osmosis have agile governance models and could implement PQC locally. Avalanche (AVAX) Employs a DAG-optimized consensus model (Snowball/Snowman), which increases redundancy and communication between subnets. Subnets (custom blockchains) can adopt PQC signatures independently. Governance is emerging, but the tech is flexible. NEAR Protocol (NEAR) A sharded blockchain with scalability and flexibility at its core. It already supports contract-based key rotation and multi-signature accounts, making future cryptographic migration plausible Tezos (XTZ) Tezos was one of the first blockchains to emphasize formal on-chain governance and self-amending protocols. It supports Michelson , a low-level functional language that allows for cryptographic primitives to be upgraded via governance proposals without forks. Radix (XRD) Radix uses a unique consensus model (Cerberus) and is focused on developer experience and modular architecture. While not currently post-quantum, its component-based DeFi engine and structured governance may allow for faster quantum-proof upgrades. Hedera Hashgraph (HBAR) Built on hashgraph consensus (not a blockchain), Hedera offers high throughput and ABFT (asynchronous Byzantine fault tolerance). Its enterprise focus includes forward-looking cryptographic considerations, and the council-led governance can act quickly. Most At Risk Monero , Shiba Inu and ERC-20 tokens, Dogecoin , Bitcoin was noted by o3 to have critical quantum-exposure risks , either due to obsolete cryptographic foundations, rigid governance, or a total dependency on vulnerable Layer-1 infrastructure. Litecoin (LTC), Bitcoin Cash (BCH), and Dash (DASH): All forked from or closely related to Bitcoin, they inherit the same ECDSA vulnerabilities without demonstrating meaningful governance innovation or PQC research. Conclusion The takeaway is not to panic, but to prioritize strategic risk awareness . Quantum computing is not a hypothetical threat; it is an inevitable one . What remains uncertain is when it will become powerful enough to break widely used public-key cryptography. For blockchain projects, the prudent move isn’t to predict Q-Day’s exact date but to build architectures that can flex when it does arrive. That includes investing in research, improving governance, abstracting cryptography, and educating communities on quantum resilience.A simulated quantum stress test conducted using OpenAI’s ChatGPT o3 model has raised fresh concerns about the future of digital assets. The simulation explores a hypothetical breakthrough in quantum computing by 2026 that would render many of today’s cryptographic standards obsolete, potentially leading to widespread collapse across the cryptocurrency ecosystem. Quantum computers use qubits, which can exist in multiple states at once due to the principles of superposition and entanglement. This allows them to perform complex calculations at speeds far beyond what is possible with classical machines. According to o3, a sudden leap in quantum capability, such as the development of a 10,000-qubit fault-tolerant machine with sufficiently low error rates, could break the security systems underpinning major blockchains like Bitcoin and Ethereum. ChatGPT o3 Warns of ‘Q-Day’ Extinction Risk for Blockchains o3 raised red flags across the crypto industry, warning that the rise of quantum computing—referred to as “Q-Day”—could pose an extinction-level threat to major blockchains. At the heart of blockchain security lies the asymmetric cryptography model: private keys generate public keys , but not the other way around. This one-way function is what secures digital wallets and signs transactions. Quantum computers might sound like another buzzword in the tech world, yet their threat to #cryptocurrency is very real and approaching fast. Scientists may differ on the timeline, but they all agree: “Q-day” is not a matter of if, but when. #Bitcoin https://t.co/SdH4NiTMoo — Cryptonews.com (@cryptonews) June 13, 2024 Quantum computing breaks this assumption. Using algorithms like Peter Shor’s , proven in theory to efficiently factor large numbers, quantum systems could reverse-engineer private keys from public data. “A chain is only as secure as its signatures,” the model warns. “Once signatures break, the chain breaks.” The o3 model stress-tested major blockchain protocols under a Q-Day scenario in which quantum machines can break cryptographic standards like ECDSA and RSA. The findings are sobering. Bitcoin: Legacy Risk and No Governance Pathway Bitcoin, which still uses the Elliptic Curve Digital Signature Algorithm ( ECDSA ), was flagged as particularly vulnerable. As noted by o3, a significant portion of BTC remains locked in legacy wallets with no quantum-resistant protections. A 2020 Deloitte study further estimated that up to 25% of Bitcoin holdings could be compromised, especially coins stored in exposed or reused addresses. Data from Project Eleven reinforces this concern: over 6.2 million BTC, worth approximately $648 billion, are stored in addresses with exposed public keys. This translates to more than 10 million wallets that could be at risk once quantum computers achieve sufficient decryption power. 🚀 @Tether_to CEO @paoloardoino has warned that quantum computing could eventually pose a threat to inactive Bitcoin wallets. #Bitcoin #Quantum https://t.co/u8DCYrTjYw — Cryptonews.com (@cryptonews) February 9, 2025 The problem is compounded by Bitcoin’s structural rigidity. What has long been praised as Bitcoin’s strength , its conservative dev culture and emphasis on protocol stability, now poses a liability. In a crisis, Bitcoin’s inability to adapt quickly could delay vital countermeasures. As OpenAI’s o3 model puts it, “Bitcoin’s survival isn’t cryptographic—it’s sociopolitical. Without preemptive upgrades, post-Q-Day drains will begin within days of the breakthrough.” While discussions around post-quantum signature schemes like XMSS or Dilithium have occurred within Bitcoin Core, no concrete implementation or accepted BIP exists. The introduction of lattice-based alternatives (e.g., Falcon) remains theoretical, with no set roadmap. According to o3, Bitcoin network survival would likely depend on one of two strategies: A politically contentious fork to a quantum-safe Bitcoin variant A preemptive key rotation or shielding mechanism that avoids exposed legacy keys Ethereum: More Adaptable, But Still At Risk While Ethereum shares Bitcoin’s cryptographic vulnerability, relying on the ECDSA, it ranks significantly higher in adaptability. The o3 model flagged Ethereum’s active developer community, rapid upgrade history, and flexible governance as key assets in navigating a post-quantum scenario. Unlike Bitcoin, Ethereum has demonstrated the capacity to coordinate complex transitions. The DAO fork, Ethereum 2.0 Merge , and the Shapella upgrade all serve as precedent for community-driven protocol evolution. “Ethereum can adapt,” o3 concluded, “but only if it moves quickly.” Still, the shift to post-quantum cryptography would require extensive infrastructure overhauls. These include wallet standards, signature validation rules in smart contracts, Layer-2 rollups, and developer tooling. Many of these components were built on cryptographic assumptions that would not hold after a quantum breakthrough. Account abstraction is only half-done The end goal is non-ECDSA accounts (multisigs, key changes, quantum-resistant, privacy protocols (!!)) being true first class citizens A lot of good work recently on aggressively simplifying 7701 to make this happen https://t.co/j66geDAoC8 — vitalik.eth (@VitalikButerin) April 27, 2025 The o3 model simulation emphasized this point, saying, “Ethereum is the only major L1 chain with a plausible fast-track governance protocol for quantum threats. But most dApps on Ethereum aren’t ready.” However, Ethereum’s programmability, a defining strength, also creates a unique risk surface. Millions of deployed smart contracts, including financial primitives on protocols like Uniswap, Aave, and MakerDAO, use static cryptographic calls vulnerable to quantum decryption. Many are immutable and cannot be patched after deployment. That said, proxy patterns and upgradeable architectures like OpenZeppelin’s implementation give some contracts a pathway for modification. But these only apply where foresight was used. Vast portions of Ethereum’s contract base may be impossible to rescue post-Q-Day without chain-wide intervention. For Ethereum to remain viable in a post-Q-Day world, o3 noted the following actions will be necessary: Roll out hybrid cryptographic wallets supporting post-quantum signature layers (e.g., Falcon, Dilithium). Incentivize or mandate critical dApps to adopt quantum-safe signature schemes in proxy contracts. Leverage Layer-2s for isolated asset migration and transaction validation under new cryptographic rules. Coordinate a network-wide “key rotation” event with community buy-in, governance clarity, and tooling support. Other Chains and DeFi: Varying Levels of Readiness Algorand: Purpose-Built for the Quantum Era Among all the Layer-1 chains o3 analyzed, Algorand emerged as one of the most quantum-resilient. Designed with future-proofing in mind, the protocol already incorporates cryptographic innovations such as Verifiable Random Functions (VRFs), and it has actively explored lattice-based encryption methods like NTRU, a class of cryptography believed to be quantum-resistant. “If Q-Day hits in 2026,” the o3 model observed, “Algorand is one of the only chains with a 12-month adaptation head start.” Algorand’s pipelined Byzantine Fault Tolerant (BFT) consensus rotates validator keys regularly, reducing the exposure window of any single cryptographic signature. More on Algorand's post-quantum technology: https://t.co/NIQEnbER0P — Algorand Foundation (@AlgoFoundation) May 27, 2025 According to o3, its structured governance and fast finality also enhance its ability to implement protocol-level upgrades quickly in the face of emerging threats. Polkadot: Modular Agility Meets Cryptographic Risk Polkadot ranked just behind Algorand in terms of readiness. The network’s parachain architecture allows semi-independent blockchains to run in parallel, each potentially adopting its own quantum-resilient cryptography without waiting for a full network-wide consensus. According to o3, this modularity offers developers the freedom to implement post-quantum upgrades on a per-parachain basis. However, Polkadot currently relies on Schnorr-based BLS signatures , which are vulnerable to quantum attacks. Still, its OpenGov system and decentralized treasury could support rapid upgrade cycles when needed. Cardano: Academic Rigor, Operational Drag Cardano presents a paradox. It is one of the few blockchain platforms deeply invested in the academic exploration of post-quantum cryptographic techniques, including both lattice- and hash-based signature schemes. o3 noted that Cardano’s extended UTXO model also provides a more modular smart contract framework, which may ease the migration to new cryptographic primitives. Post-Quantum Cardano https://t.co/MpNWSo8KWm — Charles Hoskinson (@IOHK_Charles) February 20, 2025 However, Cardano still relies on Ed25519 signatures, which are quantum-susceptible, according to o3. And while its Voltaire governance phase is intended to support decentralized decision-making for protocol upgrades, it remains under development. As the o3 model put it, “If crypto were judged on whitepapers alone, Cardano would thrive. But Q-Day doesn’t wait for peer review.” Privacy Coins: From Anonymity to Liability Privacy-focused cryptocurrencies like Monero and Zcash face a uniquely grim outlook. Their core innovations of ring signatures, stealth addresses, and zero-knowledge proofs offer strong protections against classical decryption but may provide little defense against quantum attacks. o3 noted that quantum algorithms capable of breaking elliptic curve cryptography could dismantle the projects’ anonymity features, exposing past transactions and rendering current privacy guarantees moot. Compounding the threat is the pseudonymous governance model, which makes coordinated upgrades or overhauls difficult. “Quantum computing doesn’t just de-anonymize Monero,” the o3 warned, “it breaks its reason to exist. Privacy becomes exposure.” DeFi Protocols: Collateral Damage from Layer-1 Failures Decentralized finance (DeFi) protocols, particularly those built atop Ethereum such as Aave, Compound, and MakerDAO, face second-order vulnerabilities. While these protocols do not directly implement ECDSA at their core, they depend entirely on Ethereum’s base-layer security. If Ethereum’s signature scheme were compromised and Layer-1 wallets became exposed, the smart contracts securing billions in TVL (Total Value Locked) would be undermined; regardless of whether the dApps themselves were quantum-aware. o3 summarized the cascading risk simply: “If the base layer fails, so does the application.” Compounding the issue is the immutability of many smart contracts. While some DeFi platforms use proxy architectures for upgrades, many early deployments do not, making them inflexible in crisis scenarios. Meme Coins and High-Beta Tokens: Virtually Defenseless At the other end of the spectrum lie meme coins and low-infrastructure tokens, which the o3 model described as “nearly defenseless.” These tokens typically lack development teams, formal governance mechanisms, or upgrade paths, leaving them acutely vulnerable to any sudden shifts in cryptographic assumptions. In the event of Q-Day, such tokens would likely suffer immediate liquidity shocks, with whales offloading positions to avoid permanent loss. The community might attempt to fork the project onto a new chain, but without technical leadership, meaningful migration is unlikely. Who Is Ready for Q-Day? The o3 simulation’s sector-by-sector stress test does not predict which coins will succeed in market terms, but rather which systems have the structural capacity to survive a game-changing leap in computational power. Based on cryptographic architecture, governance agility, and ongoing research, the post-quantum readiness landscape looks like this: Best Positioned Today Apart from Algorand , Polkadot , Ethereum, and Cardano mentioned above, these other coins have been noted to be well positioned in the case of a Q-day. Cosmos Ecosystem (ATOM, Juno, Osmosis) Cosmos shares Polkadot’s modular philosophy. Independent zones (chains) communicate through IBC (Inter-Blockchain Communication), allowing sovereign upgrades. Projects like Juno and Osmosis have agile governance models and could implement PQC locally. Avalanche (AVAX) Employs a DAG-optimized consensus model (Snowball/Snowman), which increases redundancy and communication between subnets. Subnets (custom blockchains) can adopt PQC signatures independently. Governance is emerging, but the tech is flexible. NEAR Protocol (NEAR) A sharded blockchain with scalability and flexibility at its core. It already supports contract-based key rotation and multi-signature accounts, making future cryptographic migration plausible Tezos (XTZ) Tezos was one of the first blockchains to emphasize formal on-chain governance and self-amending protocols. It supports Michelson , a low-level functional language that allows for cryptographic primitives to be upgraded via governance proposals without forks. Radix (XRD) Radix uses a unique consensus model (Cerberus) and is focused on developer experience and modular architecture. While not currently post-quantum, its component-based DeFi engine and structured governance may allow for faster quantum-proof upgrades. Hedera Hashgraph (HBAR) Built on hashgraph consensus (not a blockchain), Hedera offers high throughput and ABFT (asynchronous Byzantine fault tolerance). Its enterprise focus includes forward-looking cryptographic considerations, and the council-led governance can act quickly. Most At Risk Monero , Shiba Inu and ERC-20 tokens, Dogecoin , Bitcoin was noted by o3 to have critical quantum-exposure risks , either due to obsolete cryptographic foundations, rigid governance, or a total dependency on vulnerable Layer-1 infrastructure. Litecoin (LTC), Bitcoin Cash (BCH), and Dash (DASH): All forked from or closely related to Bitcoin, they inherit the same ECDSA vulnerabilities without demonstrating meaningful governance innovation or PQC research. Conclusion The takeaway is not to panic, but to prioritize strategic risk awareness . Quantum computing is not a hypothetical threat; it is an inevitable one . What remains uncertain is when it will become powerful enough to break widely used public-key cryptography. For blockchain projects, the prudent move isn’t to predict Q-Day’s exact date but to build architectures that can flex when it does arrive. That includes investing in research, improving governance, abstracting cryptography, and educating communities on quantum resilience.