China has a host of factors that make their current system very fragile. I doubt they make it five more years before turbulence hits.
It hasn't happened yet. Is there something you perceive as especially problematic now, as opposed to the last 30 years?
China has been preparing for a global energy crisis for years. It is paying off now
As other Asian economies race to conserve energy, China has huge reserves of oil and gas as well as alternative energy sources like wind and solar
I've never once heard it from somebody who correctly anticipated China's rise though. The imminent collapse story just quietly changes every 5 years or so.
If the US has an imperial rival one thing you can almost guarantee is that the predictions of economic collapse will be as frequent as they are absurdly overblown and as always, This Time It's Different.