Bitcoin's Quantum Migration Playbook — Every Proposal Compared

Google's March 2026 research slashed the qubit threshold for breaking Bitcoin's encryption by 20x, putting ~6.9 million BTC at risk. Seven proposals are now competing to quantum-proof Bitcoin: BIP-360 (new quantum-safe address type, already on testnet), QRAMP (mandatory migration with a coin-burn deadline), QSAVE (escrow custody for vulnerable coins), OP_CAT + Lamport signatures (a fast opt-in bridge fix), Blockstream's SHRINCS hash-based signatures (testing on Liquid), Winternitz Vaults (layered opt-in protection), and private mempools (available today, no fork needed). No single proposal is enough — Bitcoin likely needs BIP-360 as the foundation, private mempools as an immediate defense, and a multi-year graduated phase-out of legacy addresses. The window is open, but the clock started ticking on March 31, 2026.