It is difficult to be sure of something, but we can say that perhaps not very quickly but surely the cryptocurrency market is going to develop and in the future it will be the digital currency of the future.
In my opinion with the passage of time bitcoin will take over fiat currency also. When you have digital currency for general use why you would use fiat currency. It is up to the government, if they legalize bitcoin then I think the use of fiat currency will be reduced and finally finished. There will be only one digital currency in the world and that will be bitcoin