Chiang Kai-shek did alot of flying around in 1949. He resigned the presidency of Nationalist China in January of that year, knowwing the military situtation was spinning out of control, and taking a chance to build up his personal base of support in Taiwan. He left the government in the hands of Nationalist warlord Li Zongren (Li Tsung-jen). Li presided over the Communist crossing of the Yangtze (Yangzi) river in April and the Reds inexorable southward march.
Chiang came back to the Presidency in August, spending time in makeshift Nationalist capitals in Chungking and Chengtu.
Flying around mountainous, sometimes foggy southwest China, its not inconceivable he could have been killed in a plane crash.
So, Chiang crashes into a mountain in August 1949, what's the endgame for the Chinese communists and nationalists.
On the plus side for the communists the Nationalists have just lost their most prestigious figure. Some years ago, Joe Wang said the comanders on Taiwan were not especially good or loyal to the cause and conceivably ready to cut a deal with the communists. Chiang's crash may encourage this and we may get a united communist China in 1949.
Alternatively, there were other people who could have been potentially attractive leaders, and some of them actually may have been less annoying to the Truman administration at the time.
So, what happens after CKS crashes?
What if he survives a crash but gets captured?