Yes, got you intrigued, didn't it?
Bitcoin is a very good thing to have as an asset. Just like gold. Even better if I may say. It's secure, and unlike fiat money it actually exists and work is put into it to produce it. This makes it great to store value.
However, it cannot and will not replace current fiat money that the entire world it using. It just cannot.
Take paying a cup of coffee for example. To pay your coffee with bitcoins, one must get bitcoins first, either by mining or buying bitcoins with other kinds of money (*cough*fiat*cough). It ends up being a quite complicated process, don't you think?
Until we reach the point where paying for a cup of coffee is as easy with Bitcoin as it is with cash, we will never get mass adoption. And as far as I see it, there is no way of simplifying the acquiring of bitcoins.
For this current time, yes. Bitcoin cannot still replace fiat because many people still tend to use fiat rather that using Bitcoin or any other type of cryptocurrencies for some reason that people truly trust fiat more than they have trusted cryptocurrencies. Also, admit it or not, those earnings we have with cryptocurrencies are also withdrawn into fiat to become useful for us users so we can do conclude that still, Bitcoin and any other types of cryptocurrency cannot still replace fiat.