I am inclined to believe CCME is too undervalued already to not appreciate through the other end of any Chinese downturn. Obviously its enormous cash holdings would help as well and give CME the resiliance and flexibility to perhaps thrive in such an environment.
The main issue I see (and am not equipped to evaluate) is how sensitive would CME's fundamentals be to a significant and prolonged decrease in consumer demand (a la the aftermath of our own financial crisis).