A lot of people have been saying that based on trailer Sansa may fill the role of Lady Stoneheart and get revenge on the red wedding. I could see it since after Lysa's death, Sansa's story is very eh. However I think this would be terrible. Doesn't really fit the character of Sansa, even after all the crap she went to, would make more sense to have Arya become Lady Stoneheart (however her future story is a lot better).
Also I am pretty sad I won't get to see the creepy as shit televisted Lady Stoneheart. I think they would have pulled that off really well.
Book spoilers
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It wouldn't even make sense, how would she take revenge on the Freys from all the way in the Vale? I know the show's really getting far from the books now but I kinda doubt this rumor
I will say it'd be pretty cool to have Sansa order to have Brienne hanged though