In grad school I had a long discussion with a German professor who argued that if Guderian had not been diverted and some other forces had been deployed that Germany would have taken Moscow and, triumphantly he added, "We would have won the war!"
I replied, "Well, then we would have nuked you."
The Soviets pretty much shipped their infrastructure beyond the Urals. Taking Moscow militarily would have been of minor consequence, but again, it may have had a huge impact in terms of Stalin keeping his power.