"The US is the world power, no doubt, but it is also a mere 330M country with an ailing, poorer and poorer middle class, due to dumb politicians, and not the "market place" it used to be."
This. The US is a world power in decline, and that decline is accelerating.
It's not written in stone, though. The US has been in worse situations in the past, and we've managed to pull out of it. We can again.