Well First you have Hitler stop telling were the 2nd SS Panzer should run around to in France, pull the Forces out of Brittany and the Massif when the allies land at Marseilles and essentially begin a massive withdrawal east taking supplies with them, burning the land behind them.
This would lead to similliar conditions as the Battle of the Bulge, with the Germans in a much better position. You no longer have delays as the OKH transfers troops from Romania and East Prussia west, and the Germans may hold the Siegfried line and Aachen still.
That being said the allied positions may be considerably changed riding on their momentum, leading to a new battle. Perhaps this time Germany may not have to rely on capturing allied oil.
All that being said its very unlikely. even if you get the OKH and OKW to work together and win at the Bulge smashing all American and British Lines, something needs to be done about Patton coming to the rescue. If that is done and the victory is pushed and Brussels and Ghent are taken then you have a situation were the allied main lines are smashed, the allies in Eindhoven and other strips of Holland can be cleaned up by forces there when surrounded, and Germany may push far, with alot of luck and maybe Kesserling striking across the Alps into the Rhone Valley we have a German Strategic and Overwhelming Tactical Victory.
That being said this all assumes that my original retreat theory in France saves the Germans as much supplies as they lost in OTL.