I don't think that the Politburo can afford to let economic growth fall too far without risking its hold on power. It is not popular discontent that is the risk, but loss of support from the PLA!
A combination of stimulus and a falling AUD is likely to cushion Australia from the worst effects.
Afterthought: I am in complete agreement with ctindale on Chinese corruption. I don't think that they will have any problems with trading while insolvent.
