如果中国是中華民國，那么就可能就跟美国是同一陣营，而與蘇聯為敵。。情形馬上不同了。

In these imagined but possible circumstances, let's just imagine such a scenario: China helps South Korea invading North Korea, and the Soviet decides to join the war...

Who can say this cannot happen? And there are other logical scenarios as well.

People can only act in response to what has been given to them at the time. 

所以說，歷史不能假设。