Back when Tyler came to town with the first prophecy, I certainly thought the whole thing was a self-fulfilling delusion (on the part of more than just the witches, more than likely; but, the witches are the idiots that decide to run the show due to their "visions"). When we got the second "prophecy" (which was made up by Celeste) I was sure it was all a bunch of hogwash that the witches simply couldn't let go of, along with a few people (again, Tyler and company).
Klaus is FAR better at predecticing and "forseeing" the future than anyone (without any magic of course) with his simple painting... Even Davina did a decent job concerning Celeste and what went wrong with the Harvest's energy.
So, I do believe that this will turn into a self-fulfilling prophecy if everyone keeps on deciding that the baby truly is "the harbinger of doom". If this happens, it more than likely will never be the baby that does anything to harm anyone (the baby may even try to save some of it, but be "seen" as evil; if she grows up fairly fast), but the cyclone of anarchy that will surround this kid... Thus, the baby gets blamed--just like many historical figures.