I'm really wondering if the books bring Jon back and the TV series keeps him dead. The actor Kit Harington is insisting he's done and has apparently already cut his contractually mandated long hair. Still, apparently in the books, Jon's last words are "Ghost," apparently suggesting that Jon Snow could Warg out of his body into Wolf and save himself. Apparently the witch is also quoted in the books as saying something to the effect of man to wolf and back to man too. So maybe HBO continues to derail the series more and more from the books.
Then again, maybe this is all just HBO trying to cover up the fact that he's not really dead to add more intrigue to next season. As others have pointed out, Jon Snow is almost definitely not Ned Stark's Edited for profanity. Please do not do it again., and almost definitely the son of Ned' sister and Dany Targarean's oldest brother (not the one who was killed in the show). So he seems awfully important just to kill off if that is the case because if that is the case, he actually has a claim on the Iron Throne and actually has a better bloodline than Dany herself.