Jon isn't dead and this is why. He's got TWO different avenues averting death. One is Mel can bring him back via the Lord of Light. Two is he can go into Ghost.
This part is me conjecturing, so work with me. When other major characters have died, it was never in their last chapter of the book. When Ned died we saw his head on a spike in another chapter. When Rob died we heard tales of his body with his wolf's head sown onto it. Khal Drogo, we burned his body. Jon dies and we just fade to black. If Jon were really dead, GRRM would have had one more chapter at the wall to drive that point home.
This part is me conjecturing, so work with me. When other major characters have died, it was never in their last chapter of the book. When Ned died we saw his head on a spike in another chapter. When Rob died we heard tales of his body with his wolf's head sown onto it. Khal Drogo, we burned his body. Jon dies and we just fade to black. If Jon were really dead, GRRM would have had one more chapter at the wall to drive that point home.