For me,I think it is a long matter for crypto to be a future currency because government and other people still don't want it and don't want to accept it. Also it's difficult for the old people and those who live in a remote area to use, so it needs time to teach them and convince them to use it like a fiat money.
to be used as a legal transaction tool I think it will be difficult. but to become a transaction tool that is agreed upon by many people I think in the future we can already see it. blockchain and cryptocurrency are future transaction tools for technology solutions. we will look at it in the future.