I have got a good point on that.
in my opinion, crypto / digital currency will replace the fiat currency one day.
It won't. Fiat is mostly used to buy crypto for those who want to invest when they starting, it is more faster way than using the other way. Fiat won't replace the digital currency because having a coin s on our pocket is easier to use when you are paying offline. It will take long and very new generation can experience all digital currency without fiat exist when government agree with it.