Oh I think it's some sort of dream walking or weirwood vision too. It just didn't look like the same scene we got with the baby. With the baby the NK didn't have that thing on his back and I think he was dressed differently too. Here looks dressed like he was in the Hardhome scene, but again he didn't have that thing at his back. Still haven't gotten a chance to watch again, I may spot something to give us a clue, but I doubt it.
Another interview with Liam Cunningham in which there is more speculation about how Jon Snow will resurrected. Mind you, the last paragraph in particular makes no sense whatsoever, seeing as how there is a shot in the trailer of Jon Snow on horseback.