He could technically sit out all of 2016 or they wait and reveal towards the end of next season that he'll be back in 2017. They may focus more on Bran this year and more of Dany instead. Personally I think Jon Snow comes back in the show and in the books. I think he wargs into Ghost, and keeps his spirit. Melisandre will ressurect him as Azor Ahai with Davos' help and then it's revealed who is his parents are which would prove the R + L = J theory. I think HBO went out of its way to make Jon even more important. There wasn't a battle of Hardhome with Jon involved at all. So for them to go out of their way like that to show that clash with a White Walker was meant for a reason. Same can be said for when the Night's King starred him down.

 

I wouldn't be surprised to see older stuff turn up now. Technically Arya's events were delayed. Her role at the House of black and white happens during the 4th book and Jon's death happened at the end of the 5th.

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