Excellent posts Buzzsaw, especially the resume on page 4.
However, I still have doubts that, had the Germans had taken Moscow and Stalingrad, Russia would have collapsed. I believe that Stalin would simply have pulled further and further back, drawing thinner the German supply lines and their ability to cover the territory militarily, until Stalin was able to strike back. I understand that by the time of 'Stalingrad' much of his production had been moved well to the rear and we all know how strongly he eventually came back.
Regarding the "Britain loses the BoB" or "Britain accepts peace terms" angle, I know Russia would probably not have had support from Britain or the US but it seems unlikely that Germany could have overrun the entire country (almost = continent) with Stalin there to drive his people in his inimitable way.
On the original topic itself, I think enough has been said, Germany were defeated in their objective. I would love to have been a fly on the wall at that invasion scenario though