We asume that China is stable and the KMT had consolidated power and does not spend all its time and energy putting down challenges.
I think Tibet is still going to be absorbed into china. The Nationalists still claim it, and it doesn't have the protection of any great power.
The sowiets might try to break off East Turkestan, but they will probably fail. Their presence there is too weak. On the other hand, Outer Mongolia is porbably lost to China, even if they will claim it. They might still try to fight a proxy war there. But the most likely scenario is that they will eventually give it up in the name of normalizing the relationship between China and Russia. I don't see Chiang tying his fate to that of the western powers, once they are no longer needed to prop him up. The Chinese are much more likely to still want to go their own way and form a third pole of power. As for the Russians, they will probably panic if the nationalists win the civil war, and try to reverse the situation, but unless they imediately do something radical (like starting a full scale war) some sort of diplomatic agreement should be reached eventually. In the long run, they might get along better with the nationalists then with the communists, as they won't regard eachother as "heretics".
North Korea might survive if they keep their heads down. But a Korean War is out of the question (at least one started from the north).
The Vietnamese communists however are doomed. Communist Chinese support was crucial in them securing power in North Vietnam, and it won't be coming in this case. It is more likely that the KMT will prop up a friendly (to them) ruler. We would have seen Bao Dai stay in power, or maybe Diem.
As a side note. I don't know how "republican" a Nationalist Chinese regime would be that is not a complete US puppet. I expect that if Chiang was secure in his power, he would be quite authoritarian (in some form of confucian authoritaris, to be more precise).