There are a lot of theories. I really don’t prescribe to any. There’s a few problems I see with that theory in particular though. One that everyone says Jon looks/acts the most like Ned, him and Arya. It seems too cliche’ to be George R. R. Martin-esq. Also he’s a warg, which is not found in the Baratheon bloodline. Not to mention Gendry has been set up as the major player in Robert’s bastard line. Considering how many bastdards Robert had I’m a little skeptical as to why they would have made Jon a “chosen one” so to speak. Why would they have let him go to the wall if that was the case? He’s not even allowed to leave the wall to help Robb much less be the Anakin Skywalker of Westeros.
It’s possible just not plausible to me.
Didn’t mean this to sound snippety or anything if it came off that way.