Originally Posted by The Dark Shape
That would be awful. For one, it would mean the answer really is just for 'shock value.' "Some people figured it out? OH NO! Uhh, this!" Beyond that, an author should never change a storyline just because people have guessed the possibility of it.
GRRM commented on this, and he said the plans from day 1 haven't changed. If everyone in the world has figured it out, he still won't change it. The revelation, if there is one, is to service the story, not to be a "shock for shocks sake" type moment.
To much pointing to Jon Snow for it not to be true
1. It's pretty much a given at this point that Rhaegar and Lyanna ran off together.
2. Ned found Lyanna dying in the Tower of Joy in a "bloody bed." The "bloody bed" has been referenced in the series as being synonymous with childbirth, and it's also mentioned that "a woman's battle is in childbirth," or something to that effect.
2. Lyanna begged Ned to keep his promise to her. What promise could possibly have been so huge, that Ned would feel guilty/conflicted about it more than a decade later?
3. Dany sees a blue rose growing out of a wall of ice in a vision in the House of the Undying. That's about as blatant as it gets.
4. Arya looks like Lyanna. Jon looks like Arya. Ergo, Jon looks like Lyanna.
5. While he verbally calls Jon his son (speaking to other people), Ned, in his own mind, doesn't refer to Jon as his son. It's "the boy" or "my blood." When Catelyn asks Ned about Jon, he tells her that Jon is of his "blood." He's telling her as much as he can without telling her the truth.
6. Jon has dreams where he has to confront something, a truth or personal revelation, in the Winterfell crypt. Who's buried in the crypt? Lyanna.
7. Ned refuses to talk about Jon's mother. If his mother was really Wylla (or even Ashara), why would it be such a big secret? Why not just tell Jon? Because neither of them are actually his mother.
8. Mention of steam coming out of Snows wounds after he was stabbed. Interesting way to describe it. Dragon born?
Either way, I don't think Jon Snow will end up as ruler, not his thing.