All the US has to do to bring China down is to stop buying their cheap crap.m Which, judging from where I think the economy is mostly heading, will happen intentionally or otherwise.
One of the problems that the Chinese have is that their technology is second hand - either bought from Russia or Stolen/Bought from the US. Which means we know their weaknesses.
I mean, China finally got an aircraft carrier. Big deal. Welcome to the 1920's, China!
The US doesn't really have much to worry about but Japan, Australia, New Zealand, South Korea. Taiwan and everyone else in that region does, though.
From a purely economic point of view, I suspect China will go expansionist like the Soviet Union did after WWII. They are Communist/Socialist/Fascist/Totalitarian and sucking up one's neighbors militarily is one of the key results of Marxist based economic/social/totalitarian systems. Once they expend all of their own wealth, they have to steal it from their neighbors like the Germans, Japanese and Italians did leading up to and culminating in WWII (where the US got sucked in to preserve British, Belgian, French and Dutch colonial interests world wide
).