In reality, yes, it would have been very plausible. The Wehrmacht was the most powerful fighting force in the world at this point, the Red Army was a shambolic wreck, with little organisation and scant resources. That is why Germany was relatively successful up until it was grounded on the outskirts of Moscow. Germany did need oil, however, and thereby hence the move down south towards the Caucasuses. German supply lines were stretched to the brink, so further resources were needed, so it was vital that this was achieved first. Only once the German advance was halted did the Red Army seize it's chance, and the Russian economy and industry was geared towards defeating the German onslaught.

Sorry, but your submission has been removed because we don't allow hypothetical questions. This sort of thing is better suited for /r/historicalwhatif.