I wonder what happens to 4+2 treaty. I know that Poland wasn't among signatories of this agreement. So, today's polish Borders would be OTL eastern borders (no Kresy), and pre-ww2 western borders? These are great losses for Poland, given the fact that Stalin took the eastern part of Poland and annexed it to Ukraine, Lithuania and Belarus. Sure, if Stalin decide to punish Poles for Warsaw uprising, he could leave Silesia and Pomerania in Eastern Germany.
Stalin does not care for the Poles, moreover he regards them as political and ideological enemies, so it's not that difficult to made up some scenarios.
Some scenarios:
- failure to reach an agreement in Potsdam or earlier on Yalta
- an open Polish rebellion against the Red Army and the Lublin Committee after a successful Warsaw uprising
- successful Valkyrie shortens war for a few months, new German government manages to keep pre-war borders minus Austria in peace talks with Allies
- Morgenthau plan implemented
- Germans victory at Stalingrad extend war, the Anglo-American forces enter Berlin first and reach Oder - Neisse line. Silesia, Pomerania and Eastern Prussia are OTL German Democratic Republic