Well, short answer "bad stuff".

Long answer "BAAAAAAAAAD STUUUUUUUUUUUFF!"
But seriously, IF (and it's a big one) they somehow manage to keep the Russian populace down (remember the revolts I had in Africa?) they basically have free meals three times per day- that is lots of Fuel, Energy and Materials, not to mention manpower.
And a completely tilted balance of War.

Come to think of it I can't imagine a single good thing out of it.
But- if the Russians are not worse then the Ethiopians, they are going to put up quite the fight.

If I was part of the Allied already I could probably engineer a plan to make this crazy dash to Berlin.

But then again it would be A town that I couldn't possibly hold for long. It could work as a distraction but not as a resolutive surgical strike.

Between us, my fear is that Russian capitulation would self balance to end up as an Endless War of attrition between the two blocks: A Western coalition and a Prussian Eastern Empire...

To be completely honest I'm surprised the American War Machine hasn't put any apparent (keyword- apparent) strength in any front, but ended up commercially dealing with the Japs.

I'm nervous thinking about the possible outcome and yet can't wait to play more!