I think crypto has bright future allready since fiat is screwed because of banks and bad politics. Banks are constantly printing more fiat out of their asses while crypto has hardcoded limits. Once people will see that crypto keeps its value better they will dump fiat and start use crypto directly. At some point they might even want their salaries as crypto if fiat crashes hard.
Rothschild said "Give me control of a nation's money and I care not who makes it's laws". With crypto banks are finally going to loose that control. Thanks to decentralization no one can truly control money ever again.
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.
https://www.quora.com/Will-cryptocurrencies-replace-fiat-money-in-the-future