re: Crackpot ASOIAF Theories SPOILERS

So maybe I missed something, but the whole R+L=J....why is that truly important? I mean, maybe GRRM will get a laugh from trolling us, but what integral part of the storyline does that play (assuming Dany survives)? Jon would just go from "Jon Snow" to "Jon Sand." He's still a bastard born out of wedlock. Daenerys still is next in line to the throne, as well as Aegon (if he is actually Rhaegar's child). Jon doesn't really fit into the line anywhere.

Or am I missing something very obvious here? I just don't see any purpose for it other than a cool little twist that doesn't really mean much in the end. Hell, we already know that he doesn't have the blood of the dragon (being he burned his hand very bad). I guess the only integral part that R+L=J could play is if Jon ends up being Lightbringer.