Bitcoin and Ethereum currently lack drop-in quantum-safe signing solutions, leaving existing accounts vulnerable to future quantum computing threats. Bitcoin's proposed Pay-to-Multisig-Restricted (P2MR) draft does not incorporate post-quantum signatures, meaning the network has no immediate path to quantum-resistant transaction validation for current addresses. On Ethereum, while smart contracts can be written to verify post-quantum signatures, adding such code does not retire an account's original cryptographic key. This means that even with quantum-safe verification logic deployed on-chain, legacy externally owned accounts remain dependent on their existing ECDSA keys until funds are migrated to new addresses or contract-based accounts.