Nothing happens. Amreeka will move their tech out of Taiwan and Taiwan becomes another SAR of China. Amreeka is not going to fight for Taiwan. The only country they will possibly fight for is Australia and to some extent the Philippines. The US has already voiced its support for One China policy. Taiwan would be foolish to rely on Amreeka support. Back then when every Asian country was poor and devastated after colonial rule, WW2 etc Chinese went mad after Korean War and annexed Tibet. They took land when things were hot. What did we do? We did Panchsheel and Hindi-chini bhai bhai as the partition disaster meant Hindus became weak and no longer willing to fight. We also had a weak, pacifist clown for an PM. Other than a few Indian Army regiments, the rest were just poorly equipped foot soldiers. Without these regiments, we would have lost even more territory. That is what a mad enemy can do to regiments that care more about dress and eating manners than getting aggressive and fighting. Anyways past is past. What are we doing now?