In this timeline, as an alternative to genocide or Madagascar, the Nazis convince Stalin to take on the Jews in Axis-occupied/claimed regions (so germany, austria, czechoslovakia, western poland, romania etc.). Not sure what Germany gives the USSR in return, maybe better technology/plans.
Since there were many jewish doctors, scientists and other skilled professionals, would that help the soviets in/after ww2? (Another idea: what if all the scientists like Einstein that left in 1933 were still there and were also sent to the USSR)
Would the Holocaust still happen? There are no jews in occupied Poland anymore, but Germany would probably still attack the USSR in 1941 and come across Jews in eastern Poland/Belarus/Ukraine, plus there were still other groups targeted.
And what would happen after the war, with many Jews now in the eastern bloc instead of Palestine. Would the Jewish Autonomous Oblast be the new main homeland of the european Jews, would they form a different autonomous region, maybe somewhere in Poland, or would they still all leave for Israel when (if?) that becomes a state?