I know the theory that Jon Snow will ultimately become a White Walker is not exactly new. It was proposed in the context of end of Season 5, when Jon had died, before being brought back to life by Melisandre in Season 6 premiere. The most interesting bit about Jon's character is that he has both Targaryen and Stark lineage, with the confirmation of R+L=Jon theory.

It’s known in this series that the Night’s King was a Lord Commander of the Night’s Watch who fell in love with a White Walker. However, some believe the Night’s King was a Stark and is linked to the Stark line through blood magic. According to the legend, that’s one of the reasons why the Starks must always rule the North. In that regard, just as Dany has dragon’s blood flowing through her veins, the Starks have the icy blood of the Others in theirs. While we’ve only seen living babies turned into White Walkers, with corpses being risen as mindless wights, Snow’s bloodline could allow his body to successfully become a White Walker leader.

That means while most likely him, Dany and Tyrion will collectively defeat the Lannisters riding the three dragons, Jon will sacrifice himself and become a White Walker so that he can become their leader, and out of goodness of his heart, walk them all back up the north of the wall. What do you think?