this might happen but I think it will take a long time maybe in 10-20 years. because right now the cryptocurrency mass adoption hasn't materialized there is still a lot of rejection in some countries. most governments reject crypto because the crypto's anonymous nature will tend to be used for criminal acts. and bitcoin is also decentralized and cannot be controlled by the government. so I think fiat money will remain until later.
many countries are still considering all the consequences and consequences of using cryptocurrency as an official currency and need a lot of consideration, of course, but at this time there are still many countries that think of the negative results of using cryptocurrency when viewed from positive results can actually help the economy more modern and advanced as technology develops