To answer this question correctly we first need to take a look at what a currency needs to be.

Money needs to be:
-Easily accessable
-Widely accepted
-Has to be trusted

If we take a look at crypto nowadays, there are huge problems with all three factors.

It's accessability is a huge problem. At the moment you have to be a computer expert to use it. I always say: "if my parents understand it, than it has the potential to be accessable to everyone." If I try to explain crypto to my parents, they are rolling with their eyes, not understanding what I'm trying to tell them.

Another problem: crypto isn't widely accepted, yet. And it won't be in the near future. It's new, it's strange and fees are way to high. If I want to buy a cup of coffee, the fee sometimes is twice the price of that coffee. That's not good. Pundi X is trying to build a system that makes it possible to pay with crypto just like you are paying with your credit card, but still that's a very small project right now.

And point 3... Crypto has a huge problem with trust. For trust you need a stable market and coin. What has happened lately in the crypto with all of his volatility, it's not good for it's trust.

So, if you'd ask me if crypto will replace fiat in a short time... I don't think so. What we need is regulation and rules, so that trust can enter te market. If trust will enter the market, maybe it will be more accessable en more widely accepted. But there's a long road ahead...