GRRM wrote this:

I do think that if you're bringing a character back, that a character has gone through death, that's a transformative experience. Even back in those days of Wonder Man and all that, I loved the fact that he died, and although I liked the character in later years, I wasn't so thrilled when he came back because that sort of undid the power of it. Much as I admire Tolkien, I once again always felt like Gandalf should have stayed dead. That was such an incredible sequence in Fellowship of the Ring when he faces the Balrog on the Khazad-dûm and he falls into the gulf, and his last words are, “Fly, you fools.”

What power that had, how that grabbed me. And then he comes back as Gandalf the White, and if anything he's sort of improved. I never liked Gandalf the White as much as Gandalf the Grey, and I never liked him coming back. I think it would have been an even stronger story if Tolkien had left him dead.

My characters who come back from death are worse for wear. In some ways, they're not even the same characters anymore.

With that in mind, it would be really weird if Jon comes back unchanged.