Germany could not "win" the Ardennes offensive. They could have possibly done better in terms of driving a deeper wedge in the Allied lines. But, they were not going to terminate the US - Commonwealth alliance nor could they hope to get a peace settlement from their offensive; thus, they could not win.
On the other hand, it is likely that Hawker meant the question more along the lines of had they met some or all of their objectives such as crossing the Meuse and threatening or taking Antwerp.
The first, crossing the Meuse, is a possibility. Taking Antwerp? Highly unlikely simply because the Germans lack the necessary units to go that far. In any case, the likely eventual outcome is actually worse for the Germans. They would have been stretched far thinner than they historically were with their flanks held by a polyglot of marginally capable infantry formations of dubious quality. This would have allowed the Allies to simply counterattack into the flanks of the salient as they originally did, cut off the motorized units, and then see those units sliced to ribbons in battles where the Germans lacked fuel and ammunition to even fight.
The result would look far more like a second Falaise pocket than it actually did with the Germans fleeing the trap leaving everything behind. Doing better in the Ardennes is actually worse for the Germans.