I want the show to touch on her slowly going mad next season. But I doubt it will happen.
Next season? I don't think she starts going mad, more like she is questioning weather she wants Peace or War, Hizdahr or Darrio. At the the end of book 5 it appears she has made her decision, even though the peace was real.
I think Aegon will marry Sansa, or will be betrothed at least. With my main evidence here:
http://www.reddit.com/r/asoiaf/comments/1vsuxb/spoilers_all_the_tourney_at_ashford_and_sansas/ As well as the face that Cersei will become undone by a Queen younger and more beautiful than her, which she thinks to be Maragery, and would be very ironic if it is Sansa. One of the issues I see, is Aegon could also marry Arriane.
The thing about all of this, is that I am wondering what will happen to Cersei and King's Landing. Cersei has been foreshadowed to becoming a Mad Queen and destroying King's Landing with all of the wildfire buried underneath, this will also finally push Jamie over the edge and complete his arc, by killing his sister, for he is probably the volunquar. The problem with this is wondering when it will happen, since it seems Aegon is set to rule, which means Tommen is probably dead, and likely Myrcella. He also has to rule, and we have to have Dance with Dragons 2.0 and Danerys being there to be set up at the main Antagonist with her savage followers, including Ironborn, Dotharki, and her Unsullied.
In order for all of this to happen, along with Stannis and the Northern plot, as well as fitting in puzzles of other wandering characters (Sam and Arya). The Winds of Winter is going to have to move at a very fast pace, like A Storm of Swords, which is possible, but doubtful, since there are still two battles to take place, as well as set up The Sand Snakes and Arriane for King's Landing.