I think most people would agree with that point of view. Certainly, Von Runstedt would agree with it... I however, think, with some luck and a fewer delays - they lost 36 hours (?) trying to break through with infantry before the armor even got started - they might well have broken out. KG Peiper passed through Stavelot on the morning of the 18th and the tail of the column was hit by the arriving 30th Division, shifted down from the Aachen area - the advance was checked at that point. What if, with better luck (or better planning - hitting the line with armor instead of infantry), they had arrived 24 or 36 hours earlier, with the bulk of LAH and the rest of the army on their heels? Nobody was there to check them. And Stavelot is where the Ardennes begins to open into flatter terrain. I agree with you (and Von Runstedt) that they would have eventually been beaten - this wasn't going to break the western allies and end the war - but (in my opinion) they might well have hit Antwerp, destroyed the port, created absolute chaos and set back the end of the war for a time.