I think some of you have a gross misunderstanding of things psychologically. The crash of the USD would not only kill bitcoin, since it's primarily converted into USD to begin with, it would kill virtually every other economy on the Earth. Most of you are overlooking the very obvious fact, the world is tied to the USD.
1. USD tanks... suddenly Americans have lost purchasing power. They can no longer buy goods/services that are mostly financed by other countries. Aid to third world nations stops. Suddenly 75% of coin mining also stops because Americans cant afford energy costs. People can't afford food...
2. Lack of American investing power and consuming causes major hits to BRICK nations. BRICK nations are already suffering in near recession economies and a sudden lack of USD influx causes further depression to economies. Third world nation economies also suffer due to a lack of USD propping. People can't afford food... well people who could afford food to begin with can't afford it.
Bitcoin itself is already hugely tied to the dollar and will be for the foreseeable future. Why is that? Because Bitcoin has no use outside of the novelty. Most just don't see, that it's purely a novelty. Even those who "accept" bitcoin through one of the exchanges/store sites... are really just accepting the USD. You just don't see the go between converting the currency into USD.
Bitcoin is tied to the dollar and will be until people realize the truth. Bitcoin has no value and no use. Once people understand how to break the chains, which is to ignore the dollar completely, then Bitcoin will have real value. Bitcoin is not a medium of exchange/store of value, it's an investment tool. Anyone who thinks differently isn't looking at things for what they are. Want it to be different, then make it different.