No, because governments simply won't allow this. If there will be a crypto currency to replace fiat, it will be a crypto created by the own governments for their people. A country which uses a decentralized currency is in constant risk of sabotage, it's a question of national sovereignty and self protection.
It can work for those small countries which most people have never heard before, that have their main income from tourism or external investments, but it won't work for the average/powerful countries.