1. For the supply chain, I actually think it won't be two supply chain center, but instead it will be multiple regional supply centers. After all, the world has learned that it is terrible to put all your eggs in one basket as the pandemic has proven. For China, this actually could be considered as a loss, since China is the supply center of the world. But in the long term, it will probably benefit China because other parts of the world will finally get the development they deserve, and for China this could mean new markets after China moving up the economic ladder. For America, this probably not the kind of win they want, but still a "win" against China. Although who is going to have the last laugh is probably not the Americans, but the rest of the world.
As for tech war, it will take time, but I believe China can replace American components. The question is what to do with the Chinese companies, like Huawei and ZTE until then. IMHO, there is a need for consolidation. ZTE should probably be merged with Huawei and streamlined, and HiSilicon probably should split from Huawei and formed an independent Chip design company that sell to other Chinese tech. China should set up a manhattan project like program to speed up the semiconductor development together with Chinese private companies.
2. American gov might not be in RCEP, but American corporations are certainly part of RCEP. I don't think the American gov want or can prevent American corporations from participating in RCEP. So I think we must not overstated Chinese advantage on RCEP. After all, American economic system is capitalism, where the private corporations are the backbone, not SOEs. We can never underestimate American private corporations, they are the true strength of America. China also can't prevent American corporations from profiting from RCEP, nor should China try to do that. The beauty of economic cake is that it will only grow bigget the more people participate in it. It is the same reason why I don't believe TPP is a threat to China, but actually an opportunity. Since TPP can't prevent Chinese corporations from participating in it.
Trade war is a failure indeed, but it is a costly failure for both sides. Biden won't reverse course in the near future, so what China can do is to try to minimize the cost and find new market, which Chinese gov has been doing. Luckily, I haven't seen anything the US has been doing that is wise or fruitful. The Americans are busy tackling China that they forget to chase the ball, LOL. In this uncertain time, steady hand will win.