Fees are likely to be very high, but that's okay. Arks, ecash fedimints, liquid, etc will give us lots of optionality, lightning will bridge all the layers, & maybe signature aggregation will help most people retain the ability to have an onchain footprint of some sort. https://fountain.fm/episode/cLNMTcWrFO3hlQXk8e1K
Absolutely. Yet in my humble opinion, signature aggregation seems to be far more complex than to just keep small amounts on L2 - L3's where they can be spent easily. Using competitive banking services is fine in my view as long as we don't store large amounts there and as long as nobody can expand the total supply. It seems we assume that everyone wants to store $10 on L1 when other options for that are better.