That's for sure. We are now thinking in terms of development and can not predict what will happen in a few years. At the moment, Bitcoin does not replace the dollar. Traditional popular currency cryptocurrency. But things can change. We do not guess.
Flat is still important to pay your needs in real life , some people doesn't aware with bitcoin so you must prepare the cash for a payment. Even bitcoin replaces the flat , but flat still will be the most efficiency and easy to use currency in the world.