All right here's my stupid theory for the day:
I'm pretty sure Daenerys is gonna do at least a partial villain or Mad King turn here down the stretch, probably before a final redemption via sacrificing herself. And she's just found out that Jon is the real heir AND where his proof comes from.
So my prediction is that next episode she's gonna kill or try to kill Bran and Sam. Bran she could easily just torch when the Night King comes for him and claim/rationalize that killing the Night King was too important (NK will probably get away though).
Sam will be trickier but if the crypts go to hell there'd be opportunities to take him out in the chaos, maybe claim he had already been killed and turned. My gut is that he might survive to tell Jon about it though, or Jon will find a clue on his corpse.
TP for the daily prediction! I can definitely see Daenerys doing something irrational and evil, although I don't personally see her killing Sam.
Hmm, I guess my crazy theory would be that Bran is flown away to the God's Eye island by Daenerys (towards the end of the winterfell battle) to meet with the remaining children of the forest and the weirwood trees, while John & Arya stay behind to retreat and try to slow down the night king.
One question I'm hoping we get answered is - where the hell is Howland Reed, Myra's father? He can confirm John's background, and has purposely only devoted his family (Myra & Jojen) to servicing Bran w/o even trying to come to help Robb, Ned, etc. He also has been to the God's eye and is a magic user. I hope he shows up soon.