China has nuclear weapons, so in terms of total war the direct outcome is not in question.

The issue is Taiwan is capable of putting up enough of a fight to make it loud internationally and painful domestically. The population does not want to join a poorly run country with 1/4th it’s per capita GDP. It would be able to retaliate and hit major Chinease cities making it an extremely expensive war etc etc. And after they won they would not have an prosperous nation just a huge and angry mess.

PS: Most interestingly the people on the ground in Taiwan with the most information are scaling back military spending. So, presumably they believe the threat of war is minimal.