I would think there needs to be two major battles this season. The living v the Night King, then anybody left v Queen Cersei. So there should be plenty of opportunities for main characters to get killed off, which has always been one of Game of Thrones strongest elements, well in the first 4 or 5 seasons at least. I expect plenty of red shirts to buy the farm but it will feel like a cop out if the producers dont kill off a fair number of major characters as well.
J