“I do wonder if somehow the US and Japan could have partnered against the Soviet Union, in exchange we allow Japan control of their Eastern Co-Prosperity Sphere.”
We might have made an alliance with Japan against the Soviet Union, but most likely not while agreeing to Japan’s colonial control of so much Asian real estate. If WWII had not ended Japan’s empire in Asia, I think time would have because economic and industrial development in Asia - which Japan was doing in her colonies - was going to create moves for independence in all of them. Japan had over reached.
But then why did we suddenly care so much about Asia?