It is only a matter of time where everyone will be adept in using crypto for their everyday living. Just like using smartphone. Before, it is too expensive to buy one, now many people can afford to buy this gadget. And with a lot of crypto integrating in mobile app, no wonder we will reach the golden age of crypto where a large percentage of people living on Earth know how it works.
I think that is something that is not possible because cryptocurrency is a digital currency where its use must be through the internet, while everyday life requires instant transactions such as buying a packet of bread or candy. So the use of fiat money is still there.
To make large transactions or between regions, it might be easier to use cryptocurrency because it happens very fast, safe, and cheap. In conducting this transaction it seems we have our own bank which can be controlled from anywhere provided there is internet access.