It is too soon to tell as bitcoin is still in its infancy stage
and has yet to become mainstream and adopted by the
public.
I don't think it will replace fiat currency in at least 10 years
or more. We still have a lot to achieve and I believe this is
only the beginning of a revolution.
I think, it won' t be. Bitcoin will take the same function as fiat money to improve services to public. It will support each other.Btc can be used ad digital asset ir digital currency.That means btc can support fiat.money but not to replace. It can be used as an alternative payment instrument besides fiat money.