With the Technology being the same, we would have never lost, even without Russia. Russia destroyed their land army, but what good is a land army when you can't get it on enemy land?
The BoB ended before Operation Barbarossa, and the British were out-producing the Germans in aircraft, plus we were blockading the North Sea and keeping the Atlantic open.
The Russians were planning to attack, or at least defend their land in 1942. They were modernising their military to be ready for 1942, that's why I always say it was much better for Germany to attack in June 1941, like they did. Although it was the British that saved Russia, since they attacked the Germans in the Balkans making them divert forces from the Eastern Front and postpone the invasion of the USSR which lead to the attack going into winter. Had we not distracted them they would have attack in May and avoided the Russian Winter because they would have smashed more (I would say most but if you like at the stats they did destroy most, of a 28,800 tank arm the Soviets were left with 1506 in July '42) of the Red Army, and won.
People always think I'm disrespectful of them when I say that, but I'm not. It didn't happen like that and the Soviet Union was a great ally and bled the Wehrmacht dry on the ground.