>>one real threat China faces: depopulation
Agreed on that. Their demographic is upside-down, and given the culling of female fetuses done during one-child they're short on women of an age to produce more children. Not to mention that moving from living in rural areas (where children are an asset) to city apartments (where they're an expense) plus education has made women disinclined to raise large families in other countries - and I'd expect that to be in play in China as well.
Personally, I think the CCP has just had its nose rubbed into what the west is willing to do sanctions wise to an aggressor. I'm not sure they'd risk the hit to employment that would entail. They've been producing more steel/aluminum/concrete than they need to keep people employed (well, and regional governments get rich that way). So plenty of internal unrest.
Back to demographics. Japan had a similar issue in the 80s (remember when everyone thought they'd take over the world?). They've been in recession pretty much since then. About the only reason they're not in a depression is that they've co-located their manufacturing facilities with consumer markets. This isn't an option for China as they need local employment.
All that said, it looks like the Biden administration is taking the threat of losing Taiwan chip fabs seriously - to the tune of a billion dollars to encourage chip fabs here. Not that I think that the Chinese could just take over TSMC. It's pretty specialized and if the Chinese could build fabs, they almost certainly would. They've been focused on industrial espionage at least since the early 80s (my first brush with the issue, working at an international software company) so I don't think there are any trade secrets they don't have (unlike that USSR float glass thing).
As far as America's demographic, it's worth considering that along with that of Mexico. There's a lot of subassembly work moving from overseas to Mexico. China's no longer the lowest cost labor, and with zero-Covid, it's now a risk to have anything done there in spite of TEU and FEU shipping pushing per-unit costs somewhere close to 'free'.
