I'm pretty skeptical of Bitcoin's chances at this point. Not because the underlying technology isn't sound, but because it's been completely co-opted by speculators and "the USD is just, like, paper man!"
I think it helps not to distinguish between trading bitcoins for USD and trading bitcoins for bread.
The sum total of the bitcoin economy is
all that is for sale, including USD. From the point of view of an owner of bitcoins, they are all just products being offered for sale.
At present the bitcoin economy is heavily weighted towards sale of paper with presidents on. It makes no difference; the economy is flowing, and as long as that sustains, bitcoin will survive.