So bouncing off your theory on giants being in the Wall…. If the Horn of Winter/Joramum does wake these things then two things come to mind. It sounds suspiciously like part of the NW oath “I am the horn that wakes the sleepers”, and the fact that Sam may or may not have the real horn in Oldtown… where supposedly the base of the Hightower was made by Bran the Builder. I always wondered what the point of GRRM sending that Horn to Oldtown… I guess the Hightower must come down.