I think dollar won't collapse anytime soon, but even it happened, there won't be any major effect for bitcoin at all.
People would think ways to save their asset or how to keep their business running instead buying lots of bitcoin.
I agree that it will not collapse soon, but I disagree with regard to the low effect on bitcoin, if that happen. People will look for other alternatives and bitcoin is the best right now.
Yes, people will look for alternatives. But people will buy what they already know. And - compared to the general population, Bitcoin is only known by few people. So there will be some capital inflow into Bitcoin, but the main share will go into precious metals, land/real estate and stocks. I know for a Bitcoiner it's tempting to assume that people become easily aware of the unique properties and advantages of Bitcoin. However in practice, most people don't think a lot about the properties of money, other than that they want to own as much as possible...

So only few might realize that Bitcoin is a viable solution to currency devaluation.
On the other hand even a moderate capital inflow into Bitcoin might have a considerable effect on Bitcoin valuation, since the market capitalization and liquidity at exchanges is still quite small. But if you measure Bitcoin valuation in fiat money, a devaluation of fiat money will logically result in a numerical increase in Bitcoin valuation while its buying power might not have changed at all. So it might make sense to determine Bitcoin's worth using a different benchmark (like precious metals).
ya.ya.yo!