Honestly I suspect there would be like a year long civil war, then the American bourgeois would realize this shit show isn't good for all the assets they have sunk into this country and then bride the various warlords into signing a tepid peace treaty creating some some on EU like union for the 5 or so state that sprung up, they'd form some kind of coalition force to keep doing imperialism. They probably wouldn't be as good at it but they could probably pull it off.