- China is net food and energy importer. Look at last year for a preview of future food. The land they leased in Africa won't help in terms of climate shift, locusts, etc. Who is the number of one food and energy exporter?
- China has an aeging population, and it's already a rapid shift.
- China's infrastructure isn't as well built as other countries (see their most important infrastructure project ever being the literal definition of half-assed), and it will start degrading, and maintenance is a pain. What happens when a few dams collapse, or nuke plant blows up?
- Supply chains are moving elsewhere.
- Taiwan has enough medium-range missles to take out the Three Gorges Dam, which is effectively MAD as far as China is concerned. One could also see Taiwan being a few minutes away from going nuclear, if need be(learning the Ukraine lesson).
- The US controls space, and will solidify it's grip in the next 3 years. Nobody is within even a decade of SpaceX's launch technology. 60s solid fuel missles to launch small satellites into orbit won't cut it. Putting Mir 2.0 into orbit won't cut it. A moonbase that is effectively an even more expensive and worthless version of Belt and Road won't cut it (and obviously will provide less jobs).
- What do you do about automation, if it wipes out jobs for all the restive angry young men?
Now sure, a war in the South China Sea favors China heavily, but I don't think the "Let's party in Taiwan" scenario is winnable for them without wiping out 80% of their agriculture, their entire biomedial industry and their main banking centre, along with a bunch of nuke plants and military bases. Not to mention the US soon being able to just stack depleted uranium telephone poles in orbit to protect it's dependencies. A larger scale war in SE Asia would probably just drag the region back 50 years, and China would likely be on the losing end as all their neighbors hate them, and India for example has a very competent military.
The whole "West is in decline" narrative assumes countries are static- the US is especially dynamic in terms of social trends. We are about to end the war on drugs and undergo a massive shift in our education trends as we realize most schooling is worthless, and there is decent chance we'll go to UBI. Now granted the current expamles of UBI in the ME don't bode well, but it's kind of a hazy future.
Now if this was for Western Europe, sure I could buy it.