i see it more like this, the primary exchange from fiat to btc will be at banks, and the exchanges will be where you play with futures and other crypto. banks will run the largest ln nodes with the most funds in, and they will allow you to include your btc in those pools (this is not trustless however) they also allow you to use their sql wallets for micro payments even cheaper and simpler than ln but of course it has ln connectivity for outside the bank payments. this will be pocket money tho, and the serious funds will be held in multisig wallets where gain the bank is a signatory service also providing safe and legal backing for inheritance. as a final service there will be futures backed cards that you can lock in at a price to spend and hopefully settle at that price making the whole experience of using btc very seamless.