Perishable UTXOs and the concept you propose for their handling is an intriguing idea. However, it is important to consider some challenges and potential implications before implementing such a change into the Bitcoin protocol.

Qantum computing: While your intention to avoid quantum computing vulnerabilities is commendable, the proposed implementation may have limitations. It assumes that all Bitcoin users will upgrade their addresses to a quantum-resistant format within a certain timeframe. If users fail to do so, their UTXOs could become unspendable, potentially leading to loss of funds for those users.