I don't think fiat currencies will go away. I think we will have both fiat and bitcoin together, each with it' own niche in the same way that we have fiat along with credit cards, paypal, western union, etc.
Haha, go away.
PayPal has no future, wait a few years and they will be gone.
There support is worthless, don't accept bitcoin as legal payment proof. I think that says enough. Oh wait it can also be chargebacked...