Proposed Bitcoin quantum defenses could protect coins while leaving some legitimate owners unable to migrate or meet recovery requirements. According to NS3.AI, Glassnode's May 20 analysis identified 6.04 million BTC, or 30.2% of then-issued supply, with public keys already exposed.

A hypothetical transfer of 2.5 million BTC from large early outputs could fit within 10 blocks, but fees, competing traffic and miner decisions would determine whether transactions are included. Draft approaches under discussion include safer output types, restrictions on legacy signatures, advance ownership proofs and spending limits.

The measures remain proposals and research concepts, and recovery would depend on holders' evidence and adoption of future rules.