It takes time to learn cryptocurrency because cryptocurrency is based on technology that is quite complicated when done by parents and children. And cryptocurency cannot replace FIAT because FIAT is the legal state currency.
It takes time to trust it and this is the reason why many doesn't take a part of it. But going to the part of cryptocurrencies replacing fiat money, I still can't say if its going to happen but there's a possibility but with certain pros and cons that the government has to study first. Though there's already a technology about having cashless transactions and we are bound there. Idea can be like crypto's which will the government apply soon.