Some changes, such as relative lock time verify and segwit, have already been implemented and have made things like lightning more efficient. Taproot is a recent proposal that could further simplify the lightning protocol and increase its privacy. While there have been changes to the consensus rules in the past, users always have the option to oppose new changes and maintain their own chain with the old rules. Bip99 provides more detail on consensus rule changes. However, making changes to the consensus protocol without a clear and convincing demonstration that it is necessary is not recommended, as Bitcoin's resistance to consensus changes is a feature that makes it resistant to being coopted and corrupted. Developers should focus on making improvements that do not attempt to change the consensus protocol.