I think BTC can replace fiat sometime in the future, with how technology develops it's pretty possible to see BTC at such a level sometime later.
Stop with dreaming. Bitcoin is an alternative, how hard is this to understand? Fiat currencies will remain as main currency in the world. Bitcoin can't change that.
Possiblities there dude. If you take some long years the world belongs to Barter system Only After that Some of Asian, Greek and Roman Kings started Coin and currency system. As like bitcoin also possible in future Digital world. Adaption and many users day by day in Bitcoin forum is example for that.
You nailed it and there are more chances of Bitcoin replacing fiat currencies in not a long distant future because nothing is impossible and by looking at the pace at which Bitcoin is growing and getting more popular day by day I am sure soon we will see Bitcoin as a payment option in most of the stores.
I'm also inclined to believe it could be a real possibility, even though it sounds pretty insane at the moment to some people.
But there are still some major obstacles, think of the current confirmation times, they're pretty bad at some times.