Yep, I think that's the accepted theory on Jon Snow, Aquarius. That's why he can be one of the dragon's "heads". Not sure if Tyrion has dragon blood or even if it is necessary though. I really dint know how he's going to fit all of this into a remaining book! It seems like so much needs to happen. I keep panicking he's going to die before he finishes the series lol!
Btw has anyone read Wildcards?