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, even though the development that you mean is happening, I think it will still be difficult for bitcoin, or other cryptocurrency to replace fiat money, because basically each country has different fiat money, and also different prices.
on the other hand paper currency is familiar to all circles, of course the lower class will be more difficult to keep up with the latest technological developments, so the government must also pay attention to this, usually things like this occur in countries that have not developed, so it is still difficult to replace fiat currencies
technology developtment need hard progress ,and also not all of people will effected of its developtment.we will see unfair condition in each improvement.its happen not only on crypto , but almost all field has same condition with this.it hard and need long time to realize.