This may not actually be possible. There will still be some form of opposition to cryptocurrency. But if this opposition can be coerced into converting to cryptocurrency, then it will be very good for the crypto market prices.
I would not say it is not possible to see a lot of countries in the long run converting to cryptocurrency, though it may not seem to be what we want as a decentralized entity, but for countries integrating the blockchain technology, converting the monetary system into crypto and then it being centralized which is definite, as no government will for sure back decentralization, then it is possible. We all already know the impact this would have on the space itself and the economy generally if properly utilized.