Wow. Hate to rain on your parade, but Japan allying with China and vv, requires one of them to renounce the claims on territory they hold almost sacred.
Arguably, the last chance to pull this off is destroyed in 1937 and arguably in 1931, after Mukden. Either side to back off clashes with oriental concept of 'face'. To have any chance of pulling this off would require CCP to be a lot stronger, and only way to have them stronger is for USSR to support them more. Eventually, once Mao is defeated, 'alliance' between Chiang and Japanese will last for several more minutes.