Fiat will always be in demand and it won't care where bitcoin reaches in the future, people who are comfortable using fiat will use fiat only and not bitcoin.
In whatever way bitcoin is spread, it wont completely reach the entire population. So some don't care of bitcoin, they'll just use the fiat.
yeah however high the price of bitcoin as in the last 3 years. when the price reached $1,200 it was really a very high price. but everyone does not care much about that. they are still using fiat
unless bitcoin becomes popular or mainstream. maybe I'll see a lot of people using bitcoin