I think the potentially destabilizing impact of a major military setback is a major reason the Chinese elite won't make a move against Taiwan. For them, losing a war for Taiwan could mean losing much more at home.
Chinese dynasties have lost major wars against foreigners without collapsing. I seriously doubt the Party would collapse after the failure of a Taiwan invasion. My feeling is that any Party collapse would come out of some internal disturbance that spiralled out of control, led by a number of charismatic rebels each independently reaching for the brass ring, peeling off supporters from among the Party faithful and the military along the way. Pretty much Gordon Chang's scenario.
A I understand it, the relationship is not as hostile as we think. The status quo works well for business and financial interests on both sides.