Actually I don't think that cryptocurrencies will replace fiat money in the nearest future. There are still too many people who don't believe in crypto and don't know how to use them. What is more, government can't control crypto and that's why they don't really want it to develop as this way they will lose control over people finances.
because it's a provision goverment and nothing will change things like this. bitcoin will grow rapidly with massive adoption in various countries but on the other hand fiat will still be strong because there are backups from the government that cannot be separated from it.
not just for now, for next year maybe even forever it will be like that