Better fee estimation and fee/tx/mempool management in wallets
You are right, after about three years, we only achieved about 11% of native segwit usage, ~ 1000 BTC locked in public lightning channels, RBF/CPFP usage is about 15%/10%.
Unfortunately, most people don't care much whether they pay $0.02 or $0.2 in fees. They only start caring when fees are much higher than that. Since January 2018, we have only had that at a much lower level in April-June 2019 and at the end of October/start of November 2020. Which allows most users to just wait for the congestion period to resolve. In order to have a real change, I think we will need a real congestion period the likes of those in 2017 or even worse.
I am creating a service that will make it easy for wallets/custodians to optimize the fee of their transactions. The way it works is that users relay RBF pre-signed transactions that pay for different fees. The service then optimizes the fee by smartly broadcasting these transactions. It's already live, in beta: https://bitpost.co Anyone can try it out by following this tutorial: https://docs.bitpost.co/basic/quick-start There is a testnet version of the service too.