I think fiat is something that should and would exist alongside Crypto. We've been talking and waiting for a major adoption wave, but IMO, crypto will attain relative stability when it has come to a sort of 'understanding' with fiat. Both will become tenders for transactions in almost equal measures. But for now, we still have to settle for making the most of Crypto and the use cases that are on the rise each day. Like only recently, I paid for my meal with Tapcoin, an alt, and it was cool to spend Crypto on basic things as food.
I understand that most likely that is that the reality that we are going to see for a long time, but that does not necessarily mean that it is always going to be the case, in my opinion fiat currencies are one of the worse ideas that humanity has ever come up with, but governments love it because they get a huge advantage by having fiat currencies and being able to steal from their own population, but slowly people are realizing what a bad deal fiat currencies have been to them.
And many people are waking up to this reality and are realizing that it is better for them to hold cryptocurrencies and if they do not believe in this market they can settle and hold gold and silver which is not a bad choice at all especially taking into account their good track record over all the history of the world.