If the Kuomintang manage to pull this off for whatever reason, expect the US to support them as they're on one of the Cold War frontlines. I don't see a Sino-Soviet Split happening as Mao will be a lot more reliant on the Soviets.
By the time CKS had already gambled all his best forces in the invasion of Manchuria. By the surrender of Mukden, the Nationalists fate was already sealed.