A Dance with Dragons question

GRRM allegedly said, during a book signing: "Three heads of the dragon... yes... but the third will not necessarily BE a Targaryen...".

I say allegedly because the only source is a guy who posted it on westeros.org (misspelling "necessarily", but that doesn't prove he's lying, of course). If so, we don't need any more secret Targaryens, other than Jon Snow, of course.

It wouldn't make much sense for Bran to warg into a dragon, when he can stay there and "see" everything and communicate through crows and weirwoods and stuff we still don't know. He could easily be the "logistics manager" of the whole operation, but we won't know until the man finishes the books.

Ah, but Aegon may be a false dragon. We do not know for certain he is what he is claimed to be, only that he has been hidden away in hopes of putting him on a throne. It doesn't necessarily mean he is what we think he is. The dragon has three heads may not need to be interpreted literally, either. It may not refer to three dragon riders. We just don't know yet.

And as a further confusing possibility, there is always a chance that the other dragon riders have not been introduced to us yet. We have at least two more novels to go, and Dany is no closer to invading Westeros than she was when she married Khal Drogo. Perhaps by the year 2025 we'll know!

Bran is a possible candidate.

I can't really think of a third. I doubt Jon since he already has a Dire Wolf.

Probably Aegon.

I wish it would be Aegon! However the author likes to kill hopes of poor optimistic readers sometimes xD For the other, I don't know...

For myself, I like the theory that Tyrion isn't actually Tywin's son; that his mother was raped by the Mad King, making Tyrion a secret and illegitimate Targaryen. So the three dragons would be ridden by Daenerys, Jon Snow and Tyrion. Of course, this would also require Jon Snow to survive the end of Dance, which I like to think he will, but we'll see...