According to Foresight News, Bitcoin developer Agustin Cruz has introduced a draft Bitcoin Improvement Proposal (BIP) named the Quantum-Resistant Address Migration Protocol (QRAMP) to the Bitcoin-Dev mailing list. This proposal includes code for a hard fork consensus change aimed at migrating UTXOs vulnerable to quantum attacks.
If QRAMP gains consensus and is activated in the main version of the Bitcoin Core full node software, a countdown will commence. By the deadline, users who have not transferred their coins to quantum-resistant wallets will face transaction rejections by Bitcoin Core for any attempts to spend funds from Legacy wallets. This effectively removes these coins from circulation.
Currently, the BIP remains in draft form and has not yet been assigned a BIP number.