I mean it's not impossible, and I think that with technology evolving at a fast pace so does cryptocurrency and the whole market, blockchain will definitely become much stronger and secure in the next decade or so, and it is possible that crypto will be able to replace fiat if the government finds out the advantages of crypto and how it could benefit the economy.
Yes it is not impossible to replace fiat with cryptocurrency but mind you that fiat will not be totally remove as a medium of exchange. Think of how many years has passed with the use of fiat money and until now it is still being used effectively on making big and small transactions. Let us just say that cryptocurrency will be added to as an option or means of payment or exchange.
crypto is the eyes of the future and this is important to understand by many parties, but currently fiat will still be used in micro-payment activities that are not affordable to crypto because there are still many people who do not fully understand crypto
Yes, it is but for now we will just be positive that cryptocurrency system will be adapted to all countries around the world so that it will be easier for the system to integrate with other system like payment system.