I agree with your scenario. Do people really think in the middle of a collapse they will be able to travel freely within the US much less get on a plane and fly (and then be let in) to another country? The best we can hope for is to shelter and defend in place and somehow rise from the ashes when it is all over. I don’t even think people would be able to get to their ‘local’ safe places- gas will be cut off or astronomically expensive, travel on highways will be jam packed and/or filled with check-points. Unless you are there before and stay put, don’t plan on getting there.
It would be more akin to Jews leaving Germany before it shut down....leaving would entail being smart enough to see the writing on the wall.