Why I think an invasion of Taiwan probably means WW3.

I agree. If China invades Taiwan, which I assign a 90% chance within 10 years, I give a 50% chance of WW3 starting — which in this case means significant sea, air and ground combat between the US, China, and Russia while other regional wars kick off as well (such as India taking advantage of this and seizing territory from China).

Prepare accordingly.