[Apocryphon]

Most recent invasions by the great powers have been against pariah states (Afghanistan, Iraq, Libya) or somewhat diplomatically isolated countries that are shaky (Georgia, Ukraine, Syria). Taiwan might not have much diplomatic recognition, but it's very much economically integrated into the global economy. It's a stable democracy with one of the highest living standards. Militarily challenging the existence of such a state- that would indicate the world is slipping back into a pre-Potsdam world, where advanced nations could fight each other again.

Granted, Taiwan is much militarily weaker than China, a little similar to the Ukraine-Russian relationship, but it's also a much more stable and richer state. I think what could be comparable is if Russia really was to threaten the Baltic nations.