I'd argue that the US has already started its collapse, it just isn't recognized for two reasons:

1. Because the USD is the world reserve currency, there are people all over the world holding dollars in savings. The true inflation and devaluation happens once those dollars start being spent. The US government has been able to overspend because of this. Unfortunately, there is currently a move away from the dollar, particular the BRICS countries that are trading without using dollars. As more and more countries move away from using USD, those dollars will come back home and cause rampant inflation.

2. Because all of the major countries are guilty of the same print and spend mentality, there is a race to the bottom. At the moment, many of those county's currencies are plummeting faster than the USD which makes the USD look stronger than it really is.

I expect those two issues to merge and things will get really bad. The only question is how much longer they can keep things limping along. I also think as soon as the sharp dive starts, they will roll out a CBDC to "save the day" and most people will fall for it out of desperation.