It’ll be kinda like the collapse of the Empire in the Foundation trilogy I think. Just a gradual loss of hegemony followed by a swift turn inwards of the remaining power of empire (as the labor of the colonies begins to break free of colonial control).

As the ties to the global south begin to sever, the capitalists will start to turn inwards and the USA will consume itself. What comes out will be determined by the nature of the consumption, either some form of fascism that will mobilize the reserve labor of the core into a new, more brutal empire, or popular resistance and the proletarian revolution we were always told would happen in the developed countries. Either way, the US as we know it cannot continue to exist as it currently is.