Most certainly, tokens from the blockchain deemed as currency of value by organizations will certainly replace fiat currency.
I believe Bitcoin shall remain the currency that people use for long term investments like stock and Ethereum would be traded on a regular basis much similar to paypal or venmo.
Banks may soon issue cryptocurrency that is based off on their own private blockchain and hold currency values like how banks from different countries hold each others, similar to how US banks hold Naira in Nigeria to maintain the exchange rate.
Well, this is just an idea. There could be a lot more and the possibilities are endless.
I very well do think that the age for trading value through fiat currencies is over. The next generation must and will employ blockchains.