I think it's possible for governments to make a transition from using fiat currency, but it would be such a big mission that would require a complete overhaul of the financial system, like for example taking of the USD for bitcoin would be insane but I don't think that would be possible anytime soon.

Fiat money has been the backbone of the international economies for centuries now and it's deeply ingrained in our financial system and a way of life. However with this rise of crypto like Bitcoin, some governments and financials institutions are exploring the possibility of this huge transition from using fiat, as far as I know, El salvador did such a good starting by accepting Bitcoin as a local currency and I hope we will see many countries in the future accept it too.