The only real risk here currency revulsion. At some point there is a risk that nobody will want the currency. But the risk of internal revulsion is low. Chinese citizens have to pay taxes and many other kinds of fees and fines in the currency. They have no choice. External revulsion is a threat but here again the Chinese have opted to buy out their external dependencies. This is why China wants to own all that farmland in Brazil. It never wants to find itself in a situation where it must buy dollars in order to buy soybeans and other critical food stuffs.
People will go on and on about China's sovereign debt. They just don't get it. This is basic MMT (modern monetary theory). The bigger risk for China is that they grow too slowly not that they grow too fast.