User blog comment:The Dragon Demands/Entertainment Weekly's big spread on Season 5 - report/@comment-1600847-20150313120507

I really hope season 6 or 7 takes the time to do the big 3 omissions (Greyjoys, Arianne, and the Griffs). While my favorite characters are being well covered so far, those 3 are interesting, and if what I think will happen in book 6 with Victarion Greyjoy happens, cutting him will be like cutting Robb or Tyrion.

Though I'm sure the producers ask GRRM if the character has an important role to play before cutting him/her. After all, he's told Benioff and Weiss how the story ends in case he dies before finishing the books so they can end it themselves.