assuming the germans dont send the 4th panzer army away for critical weeks and they take stalingrad in the july rush the soviets are in big trouble. with the volga cut even if the germans dont capture baku directly they deny the soviets both the oil and the supplies coming out of persia. these would have to now come up the east side of the caspian sea which is severely lacking in communications strength.
this would result in future russian offensives being hamstrung due a lack of fuel and trucks. the germans at this point should content themselves to seal off the caucauses and use the reserves they accumulate to finish off leningrad before winter. this would dramatically improve their supply situation and free up valuable troops to be placed into strategic reserve (maybe resume the offensive the following spring and go after moscow or send a few strong divisions to italy