That's an interesting scenario. If the CCP is crushed or becomes an apendage of the KMT, that would have an effect on WWII. A more unified China, at least by the standards of Warlords Era, would be able to push back more strongly against the Japanese.
What other knock-off effects could you say would happen? I mean, the Japanese would be probably more desperate and thus they might decide to still do Pearl Harbor.
Say that, with the KMT feeling more confident and therefore likelier to take stronger lines in some of the incidents between 1934 and 1937, and Japan perhaps feeling they might need to strike sooner rather than later with the KMT growing stronger, things escalate into what is undoubtedly a Sino-Japanese War by 1936. Even if we assume that for the purposes of China and Japan that simply pushes the course of events in the war a year early (the lack of the CCP's contributions balanced by the greater strength and prestige of the Nationalists, and Japanese collaborationist government encouragement in northern China not having progressed as far by the start of the war) and that butterflies outside the two countries are minimal, then that puts events out of track - there'll be a year more of fighting before the USSR cuts down on its support for the KMT as part of non-aggression negotiations with Japan, a year more of fighting before the Fall of France (which means either Chinese supply lines to the outside world are kept more open longer relative to the start of the war, or Japan escalates matters into what would likely be a conflict with France and Britain
before OTL, with less of the creeping aggression that helped the invasion of Burma and conquest of Malaya) and as a result (assuming the earlier escalation with the Western Allies doesn't happen), a year more of fighting before Japan faces an oil embargo and the Strike South logic that lead to Pearl Harbor kicks into effect.
I don't feel confident saying who'd come out better from that, although I
suspect Japan would come out worse, but it definitely seems like it could affect what happens in China after the war. And that's just assuming the Sino-Japanese War follows the premise I set. Perhaps Hitler elects to keep up support of the KMT with them looking stronger. Perhaps the KMT
doesn't take a stronger line on Japanese aggression, instead focusing on reining in warlords while Japan goes for a more cautious approach in China in response to the KMT's seemingly greater strength, and the Sino-Japanese War instead begins later rather than earlier. Perhaps an earlier Sino-Japanese War leads the USSR to moving forces from the Far East to Europe, leading Japan to opt for a Strike North strategy... you get a lot of moving parts with a war of WW2's scale.