Looking for some speculations here. If the US policy moves from a "Germany First" prosecution of the war into a "Germany Only" one, what might the "Greater East Asia Co-Prosperity Sphere" develop into? Since we need a POD, let me throw out the following scenario:
Do you see a tri-polar postwar world? A Japan CPS as a US client against the USSR? Or the other way around? Will Japan be at peace with the US but at war with the European imperial powers? Would those powers act separately or in concert? A continued hot war, a second cold war or an armistice while still technically at war? Or does the whole CPS implode on its own?
- Pearl Harbor (they sink our fleet) and Midway (we sink theirs) happen as OTL. The US feels that any immediate threat to US territory/forces is marginalized and focuses all available forces into Europe.
- Prewar US planning assumes we lose the Philippines (for those that wish, we can lose MacArthur, too, when it happens) so the thinking is that we will get that back after we have dealt with Germany.
- With the US/Japan situation in strategic stalemate (both sides on the defensive), the European theater plays out in roughly the original way, though perhaps an accelerated timeline. (This will affect the territorial and political gains of the USSR and the deployment of the atomic bomb.)
- With Germany done, the US looks at having to start a whole new war from scratch in 1945 (possibly 1944) and decides, "All we lost was the Philippines and they were going to be independent by 1945, anyway. We aren't interested in American boys dying to recover French and British colonies, we could care less what happens to Russia out there and China is just some vast sinkhole. Anyone that wants to take the trouble out there, go to it. We've got postwar Europe to worry about."
Do you see a tri-polar postwar world? A Japan CPS as a US client against the USSR? Or the other way around? Will Japan be at peace with the US but at war with the European imperial powers? Would those powers act separately or in concert? A continued hot war, a second cold war or an armistice while still technically at war? Or does the whole CPS implode on its own?