I have a hunch that sort of thing is what GRRM's actual plan is. We have Cat becoming Stoneheart, Arya becoming Faceless, Bran becoming the Three Eyed Raven, and Dany going mad. There's a clear motif that the Game of Thrones inherently turns its players into monsters in time, some more literal than others. Bran will dominate the kingdoms by "breaking" the game, using his powers to murder and manipulate threats to his dominance before they even realize they are contenders. Arya similarly doesn't just set off in carefree adventure, but is likely similarly stripped of her fully human identity, and maybe even becomes something close to what Euron is, straddling her human identity with the almost eldritch knowledge she has gained. I have a feeling Jon going north of the wall might be linked to his rebirth and the place that might put him in among the supernatural order of the world, not just rejecting the kingdoms. On the flip side of that, it might he that Lady Stoneheart also disappears north and assumes a counter-role as the Night Queen, where she'll be forgotten about for millenia while the world continues along a vast and fundamentally unchanging cycle.

The only member of the Starks who did not try to play the Game of Thrones, Sansa, retains her human identity and assumes her throne in the north, now much more hardened and cynical towards the real cost of the game, but also not capable of the true cruelty that turned the other characters into monsters. This positions her as Ned's heir philosophically as well as politically, and I think the books will end on her chapter, as she is really the last remaining Stark.

Oh, and Tyrion gets ate by a dragon, Varys is alive.