Vaulted CEO David McAlvany said Bitcoin could disappear within the next four years because of advances in quantum computing, according to Forbes, though he also acknowledged he cannot say when such a breakthrough might actually arrive. He said Bitcoin would face an existential problem if quantum machines become capable of quickly solving the mathematical problems that protect private keys. As of mid-2026, however, no quantum computer exists that can break Bitcoin’s cryptography. The concern described in the report is tied to the pace of future quantum development rather than any security breach that has already happened. Estimates cited in the report show that a large share of BTC sits in addresses with exposed public keys: Galaxy Digital put the number at about 7 million BTC, worth roughly $470 billion, while Glassnode estimated 6.04 million BTC, or 30.2% of supply. The report also outlined an active debate over how Bitcoin should respond. BIP-360 would add quantum-resistant address types, while BIP-361 would phase out old signature support, a move that could permanently freeze coins that are not migrated in time. Supporters say that outcome would be preferable to theft and forced selling by quantum attackers, while critics see it as confiscation.

A Citi report says quantum computing could weaken current cryptography, putting 6.5 million to 6.9 million BTC with exposed keys at risk, equal to about $450 billion at current prices.

Cardano governance evaluates a lattice-based quantum migration plan tied to FIPS standards. ADA consolidates near $0.254 after a sharp selloff, but trading volume plunges over 40%, indicating cautious sentiment.

BitMEX Research proposes a quantum canary mechanism: a public bounty address that, if cracked by a quantum computer, automatically freezes legacy Bitcoin wallets. Critics argue attackers would avoid the trap, and setting the right bounty size is problematic.

Citi says advances in quantum computing are shortening the timeline for crypto security risks, with 6.5 million to 6.9 million BTC exposed through public keys and potentially vulnerable in the future.

A draft proposal called BIP-361 would phase out vulnerable legacy Bitcoin outputs and eventually freeze coins that are not moved, citing the long-term threat posed by quantum computing.

Paradigm's Dan Robinson proposed PACTs, a private timestamped ownership proof that could help old Bitcoin address holders preserve access under a future quantum-defense soft fork without moving coins first.

A new Bitcoin proposal, BIP-361, would push users to migrate funds to quantum-resistant addresses. Coins left in legacy wallets could eventually become unspendable under a phased plan.