Sure, sure, Uncle Joe was guaranteed to conquer all of Europe the moment Barbarossa started, if those pesky Americans had not interfered with their D-day and nukes, magical Siberian factories and Kremlin clone facilities ensured that the Socialist Fatherland could win any conventional war, against any enemy in any condition, all of continental Europe's manpower and industrial potential arrayed against them can't compare. Ahh, the magical world of Communist propaganda.



How they are going to attack along the whole front and make rapid advances without trucks ? And who's going to feed their soldiers ? And how much their kill ratio is going to worsen if they go on the offensive with a much less mobile Red Army and lacking all the tanks and artillery pieces they shall not produce as they send factory workers to farm Central Asia or Soviet Union shall starve ?
And speaking of kill ratio, let's give a look to the other half of the PoD: Britain shall go bankrupt and sue for peace in 1942. Which means no Allied bombing, the whole industrial potential of continental Europe shall be directed against the Soviets, the Wehrmacht can use all the men they wasted in flak defenses, Africa, Italy, and France on the Eastern Front, not to mention the fact that Italy can keep sending men there too, and Spain, Vichy France shall enthusiastically join the Axis and do the same, and there is very good chance that Turkey shall do the same. With the UK leaving the war, anti-Communist resistance movements in Europe shall dwindle to a trickle, which means less need for German garrisons, and local fascist vassals more able and willing to contribute men and material to the Axis war effort.
The Red Army is not going to win this war (winning as in "putting a boot outside their pre-war borders"). At the very best they can hope to reach a stalemate and win a decent compromise peace, when their strategic reserve runs dry.