I think that the argument goes US debt actually really doesn't matter, so long as Pax Americana is maintained. Being the global empire really helps out... until it doesn't
I guess it is possible that maybe in a generation or two Europe, Russia, China can fix their problems, get a solid working class and challenge the US.
But it really feels like the entire planet is sinking right now and the US is the best of the worst.
Maybe we need some aliens or something.