My conclusion is that Germany would still have lost the war. It would not have happened in 1945 - maybe it would have taken another 3 years. I don't think Hitler could EVER have defeated the Soviets. The need to have to fight on a second front in the west did weaken Hitler and hastened the demise of the Third Reich; however, Germany had received so many body blows even before Torch and Normandy that its defeat was assured at Soviet Hands. Operation Torch, the landings in North Africa, happened in October 1943; however, the German march eastward was forever stopped at Kursk earlier that year, in August 1943 (see Battle of Kursk). After Kursk, the Germans were in constant retreat. Normandy happened in June 1944; however, the success of Normandy, which merely established a beachhead in Northern France for allied forces to land and invade the continent, was massively eclipsed (though much less reported in the western press) by the much more successful Operation Bagration, which commenced on June 22 (three years from the start of the German-Soviet conflict in 1941) and ended on August 19, resulting in the deaths of 1.5 million Germans, the destruction of an entire Army Group (Army Group Center), the loss of about 17 army divisions, and the liberation of Belarus.
So my conclusion is that had America and Britain not invaded German-ruled Europe through Torch and Overlord, the Russians would still have won. The difference is that the map of Europe would have looked very different after the war. Instead of a democratic western Europe and a communist eastern Europe, the whole of Europe would have been painted red, and probably another few million Soviets would have died fighting.
Could Russia have defeated the Germans without the substantial assistance of the US in terms of jeeps, trucks, food, and the like? I aver that it could have, but it would have doubtless taken them longer. The Soviets proved even in 1941 that they could defeat the Germans, with no allied aid, when they caused a million casualties to the German armies in front of Moscow (aided by General Winter), so I believe they could have single-handedly defeated the Germans - in time. Instead of the war ending in 1945, maybe it would have taken the Soviets until 1950 to finish the war on their own terms - by conquering the whole of continental Europe.
Your response?