I assume the Russians would mobilize and mass most of their manpower to the new frontline in Poland, and make it much easier for the Germans to envelop them. That way the Germans would avoid facing them thousands of miles deep in hostile territory. If the Russians still have reasonable amount of manpower after 1942 operation, pull back to Poland and start enveloping again in 1943. Keep this up until Stalin agrees to become a priest or until Stalin become the only person strong enough to hold a rifle in Russia.