Several people think that Moscow would have been decisive, but I think there are lot of factors speaking against that…
a) Government and such were evacuated to Kuibysev, no big deal.
b) Communication, for example radionetwork controlling spies were evacuated to Kuibysev, and it only caused tiny break.
c) Communist had total control of news and information - if a thing like having 130+ division to start war with, and losing 160 divisions soon cannot break countrys (moral, political) back, then nothing can. They would have only played it’s significance down using media.
d) Moscow was a railway center, but capturing it would only directed all soviet forces to march towards Moscow, leading to a static consumption battle - exactly what germans needed to avoid.
e) Loss of Moscow wouldn’t have been surprise for UK, US…
Personally I think that germans should have put more power in the southern part of Soviet Union: Soviet Union had just barely enough food for population, and even with limited amount of divisions germans captured 50% of several key food related natural sources. Had germans put more divisions in southern sector, Soviet Union would have lost most of the it’s coal, food, iron ore etc. There is no way that Allied supply could have covered all the lost resources for Stalin. It doesn’t matter how many million men you have, but without food, coal etc one cannot continue fighting.