To play devil’s advocate, I think that the US is extraordinarily stable. So far, two halves of the population pitted against each other in a defective democracy, what a fantastic situation for any ruler. Plus, people have been mollified enough with, in global comparison, very high wages as to not resort to armed resistance.
If that system collapses, a non-democratic oligarchy might have its day. But doesn’t that simply mean replacing an, on its surface, voluntary participation in the reproduction of capital with a completely compulsory one? That, and overt persecution of minorities.
Sure, it will suck for almost everybody, and the new rulers might just close the borders to let no-one escape. And there will be blood, at home and abroad. But the system itself, perverted as it may seem, can survive this way for generations, if not centuries. Indentured servitude, anyone?

For a maybe more optimistic view of the future, though, here’s what Thucydides wrote in “The Peloponnesian War”:

But this was merely their political cry; most of them being driven by private ambition into the line of conduct so surely fatal to oligarchies that arise out of democracies. For all at once pretend to be not only equals but each the chief and master of his fellows; while under a democracy a disappointed candidate accepts his defeat more easily, because he has not the humiliation of being beaten by his equals. But what most clearly encouraged the malcontents was the power of Alcibiades at Samos, and their own disbelief in the stability of the oligarchy…