There is only one external event - an event that takes place outside of China - that can seriously disrupt the CCP's rule over China and that is Taiwan successfully declaring independence and international recognition.

It would be a humiliating loss of face for the CCP and would probably be followed by a desperate reshuffling within the party and perhaps even a civil war. The CCP is strong and rigid, but like ceramic, not like steel. Their only mandate rests on China's continued economic and diplomatic success. Taiwanese independence would be the nucleating particle for an explosion of domestic unrest and chaos.