How much hindsight can we bring to the plan? Moscow is necessary in 1941 IMHO, otherwise you're stuck in a long war of attrition that the Soviets have the upper hand in; they aren't unbeatable even if they hold Moscow, but the task becomes much harder otherwise. I think it was possible IOTL to take Moscow in 1941 with some different strategy, but then it is hardly guaranteed. The best situation is to be more aware of the state of the Soviet rail system and have accurate planning to build up capacity as you convert the rail system to support continuous operations further East. The major problem, as ON likes to point out, as the logistics issues. They were not insurmountable, as the Soviets were able to push in the other direction quiet rapidly based mostly in rail, because they lacked the same level of motorization in 1944 as the Germans had in 1944, but were able to travel nearly as fast somehow, which turns out to be that they understood the nature of their rail system and devoted the necessary resources to repair, rebuild, and upgrade the system as they advanced to sustain operations. So it certainly was possible as the Germans had large construction organizations and the resources to build things up had they been aware of the problem and planned accordingly, which would have enabled a much more rapid and further advance East along the Moscow axis (provided the Kiev and Leningrad sideshows were avoided).