I think Stalin and the Bolsheviks were very close to being overthrown by their own generals...had Hitler taken Moscow, I could have seen that happening. That’s why Hitler should have focused on taking Moscow, to undermine the leadership, yes they would have retreated East, but I don’t think under those circumstances, Stalin’s rule would have lasted much longer.
The capture of Moscow by the Germans would not have changed the overall outcome of the Eastern Front. The Soviets were prepared.
Most of the Soviet Staff actually expected Moscow to fall. As a result Kubyshev was designated as the temporary capital in case the city fell. It was about 600 miles or so to the east and pretty much all of the Soviet Staff and Stavka were there, including Molotov and even Lenin. It was a huge industrial town with a large population.
A skeleton force remained in Moscow along with an armored train to escort Stalin and the Generals to safety in case all failed.
Moscow itself was booby trapped. 1200 buildings including the Kremilin Govt. Buildings and even the Bolshoi Theatre were rigged with explosives as these were the first buildings which would have surely been visited by the German High Command.
Partisan groups were already set up to continue the fight and were even given special assignments after the city fell.
Soviet industry was in the process of being moved east of the Urals.