This is where you lost me, because China has no need to do this, and this leads to world war.

Why would they ally themselves with the loser Putin and Russia's tiny, crumbling economy?

On the contrary, China would at that point stay out of any other conflict.

They would say, "Taiwan has always been China, and here it is again, nothing to see here," and, "We do not support the use of force in Europe."

"Hey, Joe, just a courtesy call. We're invading Taiwan right about now, and if you just stay out, we'll give you a nod in the Russia thing. Yeah, yeah, I know, we'll guarantee continuity and honor all contracts."