The storyline seems plausible, given a few criterias:
- Pearl Harbour didn't happen. US didn't join the war.
- England doesn't get supplies, because german subs control the waters.
- Battle of Britain was succesfull for Germany, crushing the RAF (this could have happend, claim some, if Germany attacked earlier in the war.)
- Britain surrenders, letting Germany concentrate all their firepower on the east front.
- Germany doesn't fail at Stalingrad. Either by having a succesfull blitz in the summer, or by being more prepared for winter-battle and being able to support supply-lines.
You probably thought of all this, I'm just thinking loud :P
Looking forward to this, if it's done properly.