The English Channel becomes a bloodbath with German and British planes/ships cluttering at the bottom of the ocean. Germany and Britain may soon be in serious shortage of planes and ships. It's uncertain which would come on top. But the British are likely to suffer against the Japanese. Invading the southern islands was always insisted by the Japanese navy, but they feared that America wouldn't allow it. Prevent Pearl Harbor, and the Americans probably won't declare war on Japan, though FDR would be much more hostile to the Axis. Britain COULD eventually fall to the Germans, but it would come at a MASSIVE cost. However, there is a big problem in the East. OTL, Hitler knew that invading the Soviet Union as soon as possible was essential because he knew that the Russians would only get stronger as time would come. In due time, Stalin will feel that Hitler is no longer trustworthy and may seek to potentially expand. When the British Empire falls, the Russians probably invade Germany when their forces are at their best. And the Germans have no hope of winning. It'd be a bloody battle, but in the end, much of Europe falls to Stalin's whim. And Europe is conquered, the Soviet Union invades Japan. Again, bloody battle, but the Russians conquer Japan. However, Stalin is likely to dispose Hirohito because imperial rulers were not suitable as communist-puppet overlords. Hirohito's fall means absolute chaos in Japan against the Soviet troops stationed there. And America wouldn't intervene to save the Axis, though FDR would probably be regretting the outcome through the rest of his presidency. So now, the Soviet Union has a firm foothold in Europe and Asia (Mao will still come on top in China), making it the most powerful country in the world. And Stalin will surely cement himself as a grand figure in the communist puppets he sets up, as well as unprecedented support from his own people. Hate to say it, but Pearl Harbor and Barbarossa were probably significant in the preservation of Western culture. Otherwise, the Soviet Union comes out on top.