That Glover dude reasoning is kinda flawed, so the Bolton betrayed Robb leading to the death of his brother, and partially to invasion of the ironborn. (the ironborn would prob. have invaded the north even if Roose didn't betray Robb, but with Robb alive they wouldn't have stood much of a chance really.) So sticking with the dudes that are just as much the reason, if not more him and his people suffered seems faulty. Basically the glover just wanted to stick with what he presumes is the winning side. Pretty sure if Jon/Sana had won more (important) houses to their cause before meeting him he would have joined them. Not that he needs to join them, cause really house Stark will so forgive the Glovers for not keeping their oaths cause you know the others are coming and stuff. I'm guessing we can say goodbye to the awesome manderly's and probably the Great Northern Conspiracy in the show. Unless the Smalljon is the mastermind in the shows.
My guess is Sansa letter will have been send to Littlefinger. After all it's not like they can just show the knight of the Vale marching to moat cailin, and then have them march back doing nothing... It's too pointless, and it leaves Littlefinger with no real plot to continue. Brienne will be send to the Blackfish and again, judging from the promo trailer my guess is the Tully will hand over Riverrun as in the books, but instead of disbanding their army, march it straight up to winterfell to join Jon/Sansa in the show is my guess. My guess: Fight of Winterfell wil start with Jon unaware of Sansa politics attacking winterfell. Just when stuff seem unwinnable, the joined forces of Riverrun and the Vale will come.
Arya will survive, and judging from the promo trailer of next week episode go after the waif in retaliation. I guess you can only wit in the dark for the waif to show up before getting bored of it. Guess the scene with Arya from last week was just to show her resolve and show she know the FM are coming for her.