This proposal is encapsulated in an early draft BIP (Bitcoin Improvement Proposal) found here. The primary motivation behind this idea is to address the economic inefficiencies associated with unconfirmed transactions by enabling them to be made invalid beyond a specified block height or block time.

The need for such a feature is predicated on the current and potential future demand for asset swaps within the Bitcoin network, which could lead to competition for block space between these transactions and traditional Bitcoin transactions. By making asset swap markets more efficient and reducing their on-chain footprint, the proposed opcode aims to foster a more decentralized ecosystem and mitigate the push towards centralized solutions that may offer higher operational efficiency but at the cost of centralization.

Before moving forward with the draft implementation of this proposal, the author seeks feedback from the Delving Bitcoin community, acknowledging their greater experience and expertise. The goal is to identify any potential issues with the concept to ensure its viability and effectiveness in achieving its intended objectives.