Did the Allies conduct Operation Dragoon in August?
Even if they lost the Airborne and embarked Divisions, they still have the remainder of 3 million troops available to land by the end of August.
Southern France is lightly defended and IOTL the ports of Toulan and Mariseille were captured and returned to service along with the railways in Southern France.
Indeed, as Roosevelt mentioned there troops in the South of France by November, but with no Northern invasion the Germans can allocate far more forces to the South, preventing the decisive victory of OTL's Dragoon.