The fact is that the future is a loose concept. It is necessary to immediately fight the time in question. The fact is that I can not imagine that my grandfather or grandmother use cryptocurrency in stores or on the Internet. For a certain category of people, paper money will still be in demand.
I think that our grandmother won't use Crypto as a transaction tool. surely the fiat money will still be used again. because the old people did not know the name of technology well. so implementing crypto for everyday transactions is indeed difficult.