The Corruption of Danni has been obviously coming on since she had molten gold poured over her brother's head, and moreso since she demanded that Jon bent the knee - Nothing about this surprises me.
As for who *gets* her... I think it will be Jon. She's gone into full paranoid mode, and no-one else will be able to get close to her.
(Tyrion may be executed... hope not, but who knows. (see below))
And after Jon's killed her, he'll renounce the throne and start a new Night Watch (Maybe - dunno if they'll be needed now the
Ice King Night King is dead... (Although, is he EVER really dead??) Sansa will then take the throne because Bran is away with the fairies... (maybe literally!)
Dunno about Arya though... I really hope she survives. But I can't see the series ending WITHOUT a Stark ruling the 7 Kingdoms.
(Maybe Sansa and Tyrion *will* get married - joining the two houses agian? And we'll have the unthinkable of not only a woman on the throne, but an "Imp" as her King. (Oooo diversity!!!) There's certainly been foreshadowing that she's been treated like nothing but chattel by all the men in her life BAR him.)