That would leave a negotiated settlement between America and Japan or America persuing a Pacific First strategy
If the Americans are going Pacific First, then Chiang will get the American help to restore the KMT to power
If somehow, the Japanese and America come to terms, then the Japanese in China will have to surrender to the Chinese and Chaing gets control over the country
Korea is never partitioned and the US probably gets to occupy it. Vietnam I'm not sure about. The French will try to get it back but doubt if they're strong enough. The Chinese will probably object to that
Half a chance the U.S. agrees to Japan's surrender per Atlantic Charter, allowing Japan to keep an Emperor (if not, necessarily, Hirohito).
So, without Sov weapons & equipment, Mao loses the Civil War. Korea, as noted, is not partitioned.
Vietnam probably remains unchanged, unless this all happens while FDR is alive & he cuts a deal to recognized a free (fascist, "anti-Communist") Vietnam--or he, or Truman, tells France to go screw, recognizing France needs the U.S. in Europe as much as the U.S. needs France. (Postwar, France needs the U.S. rather more....)
If Vietnam is a U.S. ally postwar, does this keep Burma from going Communist?