This question presupposes that a collapse of the currency will lead to a Mad Max-style anarchy scenario. Anything could happen, and sometimes countries experience unrest during a currency collapse and debt crisis, but normally it isn't the case that this leads to a total collapse of society. What is the case is that imports get more expensive and exports become more competitive. So there wouldn't necessarily be a need to flee America. Instead there would be some nasty rising prices on imports and commodities. But on the plus side, you would have a better chance of succeeding at setting up a manufacturing plant and exporting your goods. So if you're keen on opening a factory and shipping stuff overseas, the U.S. could be a good country to be in when the dollar weakens.

The effect of devalued dollar reserves on foreign countries is less clear and probably depends on each country. But it also seems unlikely that it would lead to a mass collapse of order. In 2008, debt collapsed in value across multiple countries- directly affecting consumers- and none of them fell into disorder.