I believe that bitcoin will never replace fiat because fiat is a well organized money and fiat system is supported by every government around the world and each money that a country have has its history behind it.
You got the right answer Sir. True, seeing the faces of our dear heroes and presidents in fiat is history in a paper. And kids will see that letting them know the history or origin of his country.
That's true but I think there should be some alternate for fiat currency, and bitcoin can be one of that, the only thing is we need mass adaption and awareness among the people.