Maybe delay the inevitable conquest of Germany (from the Allied side at least) for a few months. If that, even. If the Germans had taken Antwerp their few troops would have been stretched to the limit and Allied air superiority would have allowed them to pick these guys off one by one. Yes, the loss of Antwerp would have delayed the Allies getting supplies up to the front but not by much. The Battle of the Bulge was too little too late.