User blog comment:The Dragon Demands/Season 5 trailer officially released/@comment-1600847-20150130164618/@comment-5014364-20150131153627

Runnning theory is that several plotlines which *should* have been in Season 5 were backburnered until Season 6, because they're waiting on a Season 8 confirmation (and if not they will remain cut). -- Even though some of these are kind of difficult to delay: A6, Arianne, the Greyjoys, etc.