I'm inclined to agree, a war would be very bad for China economically; I can't see them hazarding it. But nationalism can be a compelling motivation. This was impressed on me several years ago when I met a Chinese-Canadian woman in Minneapolis. She could not understand why China (the mainland) shouldn't have the right to control Taiwan, nor could she understand why the West had any business interfering in the matter.
I tend to agree with her. Did she also suggest that the U.S. had no business chasing the Japanese out of Manchuria in the 1930s?
That is the real issue at stake is pride. Would they start a war over it? I don't think so. If China was ever to start a major war, they would invade the middle east. Their demand for energy is a compelling factor.
It would be a lot easier to defeat the Chinese in the Pacific then it would be to prevent them from overrunning the Middle East.