The writer in his interview repeatedly stated that he was an opponent of the concept of the resurrection of dead characters - so, it seems that I could hardly rebuilt from the dead John Snow.
"No matter how I adore Tolkina, it always seemed to me that Gandalf was worth staying dead. In the "Brotherhood of the Ring" there was a wonderful scene in which he fights with a balrog in the Cozes Duma and falls into the abyss, and his last words - "Run, Fools!". This is such a strong scene! And then he returns as Gandalf White, improved. And I liked the White Gandalf much less than Gray, and it seems to me that it would be better if Tolkien left him dead. "
"I think that if you return the character if the character passed through death, he was very transformed. My characters who returned to life have changed - they are in many ways no longer the people that before. The body may be, and moves, but the spirit has changed, transformed, and they lost something. "
However, since Martin has already stated that in the creation of the 6th season "Games of Thrones" did not take any participation at all, his views on the problem of the resurrection of heroes remain purely theoretical - it is likely that the Showranner will decide to reward John Snow for the suffering of some wonderful storyline.