Assuming China post Mao does not acquire is current leadership & government system, but instead a dysfunctional hardline socialist leadership or kleptocracy, or maybe a fragmenting decentralizing failing state.
What are the global effects economically & politically? One is the US acquires its cheap imports elsewhere, boosting other Asian, American, or African economies. A second is the dynamics of international politics in SE Asia and pacifica will be very different. The main concern in the S China Sea being mainland based piracy.