Im sure Stalin had a slight idea of what might happen to the pact after all you dont postion 3 million troops on the border of a country for nothing.

It may of been the planned withdraw of the soviets during the first half year of the campaign that stopped the Germans from advancing any deeper into Moscow.

If the Soviets stood and fought insteed of melting away at the beginning of the invasion then there would of been a stong chance of them being destroyed.That would leave nothing to stop the German drive towards Moscow.