An interesting question seems to have come up mainly, could the allies have won the war without the US or Russia?
After giving it some thought I'd say that depends on the scenario one constructs and what one means by" winning"
For example, if you take the US out of the war does that mean Imperial Japan confines its aggression to China( the only way to not involve the US is to not attack us) or do they carefully attack only British interests and avoid US ones?
If Japan doesn't attack the US or British interests and confines its aggression to China then I think the allies still win total victory over Germany and Italy no question even without the US, although it's more costly.
If, on the other hand, Japan attacks British interests but not the US( seems unlikely but posible) things become a bit more dodgy.
Now alot more variables come onto play.
For instance, in this scenario is the US still supplying the allies even though they are not actively fighting( it's hard to imagine we wouldn't) if so then I think the allies win for sure.
Also what do we mean by winning in this scenario? Even with no help of any kind from the US it's hard to imagine Germany, Japan, and Italy taking and occupying Australia, Russia, Canada, and Britain.
Even in the far fetched scenario that Japan attacks British interests and avoids US ones and the US does not even supply arms for some reason my money is still on the allies to at least hold the lines where they were in early 42 and most likely role most or all of that back eventually although it's going to be one tuff slog, that's for sure.