Conventional Warfare is expensive and destructive. Economics is the new battlefield.
You see Vlad's blunders with a "lesser" nation that is basically next door, and you think Xi wants those issues with an island that can fortify itself against a siege?
They would have to contend with:
-100 mi of open sea that can be mined and guarded by opposing naval assets
-Supply lines that need to be protected in said 100 mi corridor.
-Having to secure landing sites via amphibious means, which will be a bloodbath.
-Having to minimize losses in infrastructure during combat, if the objective is to capture the semiconductor plants.
-Resentment at home. War is a hard sale without a casus belli to get people fired up, a reason to die for. You can try conscription, but people will try to buck it at some point. It's easy for a something like a US Marine out of Michigan to kill a "haji" who might as well be a Martian to him in language, appearance, and culture. How do you sell that your enemy is someone who looks like you, talks like you, and basically has the same culture as you? It'd be like getting that same Marine and convincing him to invade Windsor or Ohio.
-Fronts that could open up; The West will most most likely employ the armed forces of Japan, South Korea, The Philippines and other Allies in region to shore up defenses around Taiwan. Though I don't think we would have a crazed MacArthur type who would push to up the ante, but you'll always have hawks. What if India decides to get ballsy and invade from the west? A 1950 redux of bulldozing Pyongyang? Japanese landing boots on Manchuria?