^^^^^^^^^^^^^^^^^^
Bran is generally considered a main character in place of Sansa, though that's partly colored by Martin's statements that Bran was THE main character when he was first devising the series. Take that for whatever it's worth because he sure hasn't had much to do lately.
In the books Momma Stark makes kind of a creepy return too. Wonder if that'll happen this year.
I`m pretty sure i`ve read/heard the producers say that they won`t follow Katlyn`s story
The point at which she came back in the books and how she effected the story has passed. They could reintroduce her later in the story but I think they just ignore "lady stoneheart"
There's speculation that Sansa is going to take on a lot of Lady Stoneheart's plot (minus the death and resurrection bit). That would make some sense story-wise, and would help explain the reason for some of the controversial changes to her plot (like having her raped and abused by Ramsay). I'd be cool with seeing her cleaning house on some Freys and Boltons, since she really hasn't done much but have a series of awful things happen to her so far.
I think I'll be disappointed if they decide the way to redeem / grow Sansa's character is to have her turn into a vindictive bad-ass.
We've seen that she's not a conniving court mistress like Cersei or Margaery. She's not cunning. But she's also not bloodthirsty. I want her character to have agency, but I don't think the only way to make a female character strong is to have her become a killer.
What's interesting about that is that in the books there've been some indications that she is becoming that cunning political actor - she starts playing the Lords of the Vale to help Littlefinger keep his position there, gets engaged to the next in line to inherit the Vale, etc. The show seemed to be moving in that direction 2 seasons ago, but then took the abrupt left turn where she gets abandoned and abused in Winterfell again.
I disagree that making a female character strong via vengeance implies that that's the only way to do it, especially when you're naming alternate examples in the same paragraph. But I think we agree that Sansa's character is pretty much a mess at this point and whatever ultimate arc they're planning for her hasn't been set up very well over the last few years. Unless of course that arc is "you're young and naive, then awful people are awful to you, then you die" in which case they're all over it.