i get the R+L=J theory, but....

[Syphon of Oor-Tael]

perhaps Arya could end up as Sansa's executioner but with neither realising the identity of the other. Finally reunited but not knowing one another. How bittersweet is that?
Arya as a queen herself seems far fetched. We'd have to get her b ack from ...i forgot where she is as per the end of the last book.. in a short time. She could indeed be queen in the north but Sansa has a better claim. Then again, who's to say she doesn't forget her ownidentity too?

 

[Hilarious Joke]

I'm hoping that Sansa and Arya will eventually finish up on the sweet side of the ending, having gone through so much bitter, so to speak.