I agree that the US is not the center of the world, however the international currency of the world is USD.

If the USD were to collapse (which it won't) a lot of very scary stuff will happen in a lot of places where the USD is the main currency (mainly the US). Probably as bad as what happened around Katrina or worse. I think most of the local IT infrastructure in the US would not hold up. It's pretty hard to trade BTC without access to the blockchain.

As for the rest of the world I am not sure what would happen (assuming local currencies don't crash). I am assuming most parts of the internet will stay up.