[GreenLantern]

I always thought the dragons out of stone was referring to dragon glass. John would at some point figure out how to either make more or harvest it or whatever as it is the key to defeating the white walkers.

There is a theory out there that the Knight WunWun kills before John is stabbed has a blue comet as his sigil across his breastplate, at the time of his death it is red covered in blood. When they stab John the wounds 'smoke' in the cold and the salt is referring to the Knights Watch who are crying while they do it. I feel that one is a bit of a reach, but very cheeky of Martin to put a comet as Ser Patrick's coat of arms.