What are you trying to say actually? everything that you said is not matched from one to another.
it was like, you're trying to say that cryptocurrency or digital currency is our future but, at the same time, you said nobody can replace fiat currency.
and decentralization? what is wrong with that?
I can confidently say that any day any time, i will always prefer cryptocurrency over fiat, because i am in full control of my asset and i can decide to send it or transact with it at any time that i like or prefer.
But cryptocurrency has a lot of flaws compared to fiat.
the users need to have a little knowledge on computer or technology, while fiat is not.
the hacker is out of control.
and many more