Even in the worst possible case, I still don't see what could prevent the U.S. from simply cranking out a new huge Pacific navy and overwhelming Japan. Yes, the production would take a few years to ramp up to full capacity, as it did in reality -- but once it did, I can't imagine what could save Japan from being overwhelmed.
Ending the war in China wouldn't have helped the Japanese at all, even if they linked with a victorious German army in the Far East. An additional land army at their disposal could not prevent the U.S. navy steamroller from eventually reaching their home islands, whereupon they would be bombed and starved into surrender. (If not for the atom bomb ending their agony even earlier.) The Japanese islands are so exposed and vulnerable to any superior naval power that they could be lost even as the world's mightiest army is watching helplessly from the Asian mainland.
The only theoretical chance I see is if Germany somehow conquered both the U.S.S.R. and Britain, and then threw all its resources on a crash program to build up a huge navy of its own and help the Japanese. But I'm not sure if they'd be able to outproduce the U.S. even in that case. (And note that this would require a vanishingly improbable long continuation of the Germans' lucky streak.)
In the context of this discussion the important thing is what could be reliably predicted in 1941, so we should ignore the possible effects of the atomic bomb.
Assume that the entire U.S. navy is destroyed in January 1942. A reasonable realistic scenario, if everything went really well for Japan, may be this:
I was very interested in the discussions and opinions that grew out of the last time this was played, but find digging through 800+ comments for a new game to start on the same thread annoying. I also don't want this game ruined by a potential sock puppet (whom ever it may be). So here's a non-sockpuppetiered Irrationality Game, if there's still interest. If there isn't, downvote to oblivion!
The original rules:
Enjoy!