The Germans couldn’t have won in The Bulge. Once the skies cleared they were done for. And the fact that the Bulge really resembled a funnel in that the farther the Germans penetrated, the narrower their front became. What’s truly stupid, if I may say so, is how Eisenhower chose to counter attack. Much the same as six months before in the Falasie Pocket in France where the Germans were surrounded and virtually annihilated they found themselves in a similar situation in The Ardennes. The Germans seemed to have a positive talent for creating salients . And anyone who knows enough about military tactics knows a salient in your enemy’s line can be a dangerous thing.
Basically the Germans had pushed aside Bradley’s First Army
to the north and Patton’s Third Army to the south. Eisenhower could simply have ordered Patton to attack to the north and Bradly to attack south and cut the Germans off. Instead he chose a frontal assault that, ironically caused more American casualties then initial German assault.
They very much could have won it, but they couldn't maintain the speed they needed, because allied command (attribute it to whomever you like) concentrated on restricting German movement via obstructing the bottlenecks (Bastogne being the best known). Even if the Germans had retaken Antwerp, they could never have held onto it long enough to accomplish their objective of starving the US and British (okay, and French) armies.
In a "A Soldier's Story" Bradley noted that the attrition rate of riflemen was enormous, but a massive mobilization was still going on that would have led to a large percentage increase in US troops in Europe if needed, even with the approaching denouement in the Pacific theater.
By the time of the Bulge, the entire southern coast of France was in US hands, opening up additional avenues for shipping in cargo. Ultimately, even a German victory would not have done more than delay the end, and even that wouldn't have been for long.