As for the first question, it's not a problem for China specifically because their leaders seem competent. But more generally the problem of power transfer in case of poor results probably has lots of different solutions that haven't been tried in the past, especially now that we have more technology available. One interesting thing China does is have lots of surveys about local policies, which seems to me like something easier and more practical to have now that everyone is online.
In any case, that question is not too different of a problem than what to do when the government in a decentralized democracy such as ours has been taken over by all sorts of interests that are not aligned at all with the population's interests.
Decentralized systems like the one we have are very hard to fix incrementally precisely because they're optimized for stability in the face of constant growth, and we've reached a point of no growth, so the stability starts working against it as it makes the necessary changes harder to enact (since it's very decentralized). Like it or not, the most logical solution for this is more centralization of power. And this will likely happen in the coming decades. It's better that it happens willingly than unwillingly.
Optimizing society for growth is a dead end (collapse or extinction). It's completely irrational. The most sane approach is sustainability.
> Its subjects are its assets. Their proprietor’s purpose is to preserve and improve this human capital—hence, salus populi suprema lex.
People are people, not assets to some monarch. Sorry, I can't stand behind some backwards 17th century thinking.
He is also completely wrong about economics. Economics is not a science that Yarvin thinks it is.
And China's social credit system looks like "indirect through other human beings", at least in part.