Am going to speak from the point of recent happenings and it is that, China is really and firstly more interested in making the BRICS currency their own local fiat currency, of which is the Yen. They want to dominate and along with other interested countries, create a new world order that means dedollarization in essence.
Yuan, not yen, the yen is Japan's currency!
This is actually funny when people talk about de dollarization and China replacing the $ but half of the population doesn't even know their currency name!
4.If China takes over Bitcoin, most of the BTC developers, miners and users would fork BTC and move to the forked version of BTC. The version of BTC that was taken over by China would become useless and worthless(which makes the whole process of "taking control over Bitcoin" totally pointless).
As long as you don't change the algorithm the attack will not cease, and changing that and render all legit miners useless will be just as bad, and even so will just earn you a bit of time till they build the new asics. Even PoS will not be a solution, they could simply buy their validators and good luck stopping that!