In the current time Bitcoin can't exist without fiat because bitcoin is relative to USD and at least for the nearest future one can't separate the two as different entities because BTC is very much depended on fiat.
What? Bitcoin was created to exist without fiat. If sellers start accepting Bitcoin as a payment for goods and services, there will be no need in fiat money at all.
Thats right of course with that condition we will no longer need fiat if bitcoin can be used anywhere and anyone accepts payment with
bitcoin then of course people will be more comfortable transactions using bitcoin and fiat will no longer be used