I don't think banks will go out of business per se. But let's...

I don't think banks will go out of business per se. But let's assume that Crypto will replace Fiat currency for the sake of the argument here. Doesn't that mean that the people with the most Bitcoin, Etherum, etc etc.. will be the new banks? They would set up institutions where they can lend you an X amount of Bitcoin to buy your house and car and you would repay with interest.
The advantage some Cryptos give is that it cannot be printed on a whim of whoever is in charge at the time.