If China attacks Taiwan it is a win-win situation for them.
1. They get Taiwan (I really don't see us getting involved other than as arbitrators because of the WOT)
2. Get rid of their excess males.
Actually, Chinese don't have a chance in hell of taking Taiwan any time soon.
Battle for Taiwan would be an amphibious assault. The history shows amphibious assaults required the following :
1. Sufficient Amphibious Transportation capacity
2. Complete Air Superiority of the Theater of Battle
Chinese at this point do not have enough shipping capacity to mount an invasion that could suceed. They've been adding tonnage to their fleet like mad lately, however, they'll need another 7-10 years worth.
In the air superiority arena, they're even further behind. They're trying to compensate with a large number of medium range ballistic missiles pointed at the island. Their best chance is a surprise strike on the Taiwan airfields where the F-16 there get destroyed on the ground. Barring that, even if US Pacific Fleet didn't intervene, Chinese could only have contested airspace over their invasion fleet - not even close to achieving superiority. Hence, the vehement Chinese opposition to the proposed AEGIS sale to Taiwan - the radar system could server as critical early warning and tracking node in the Taiwanese defense network that would completely make a suprise destruction of Taiwanese air force an impossibility.
Without the air superiority over the straigths, Chinese troop carriers trying to cross would quickly go to the watery graves. If the pacific fleet's carrier battlegroup(s)intervened, Chinese are looking at completely hostile airspace over their invasion fleet - buncha very expensive scrap metal. I wouldn't worry about Chinese invasion of Taiwan any time soon. I'm worried about Chinese invasion of Russia. Russians have been bulding up their nuclear arsenal not because they're scared of us - they're scared of the Chinese. There's already 20 mil illegal chinese inside Russia. Only thing that's stopping the Chinese from "going to the help of their oppressed countrymen" is the fact Russians would nuke them as the first regiment crossed the Russian border.