No, because governments simply won't allow this.
I also believe this is the main reason, Bitcoin is decentralized, they won't be able to control it.
The purpose why government is created is to control us through their regulation, fiat will always remain as the money in this world regardless of how much improvement in technology we will enjoy. Let's remain realistic and even bitcoin soar nothing will change, so let's enjoy bitcoin as an investment as well to take advantage when it moons.
You're totally right because one the main reason why they governments are against bitcoin was because it a decentralized coin and this is the reason why I believe bitcoin can not replace fiat currencies except if the governments did issue their own national crypto currency as the IMF Boss advice them but it now there's no update about the countries which said they will issue a national crypto currency.