...is that I've always WANTED to see this conflict between Jon and Dany, which failed so miserably to be written with any complexity and nuance in the show. I don't know if Jon will die or exile himself (I do think it's entirely possible he will kill Dany in the end, if he considers her a threat to the realm), but I severely doubt he will take the Targaryen name and carry on the torch. I think the Targ line will die with him. But it's going to be interesting to see Dany faced with the fact that not only does Jon arguably have a better claim to the throne than she does, and not only is he more appealing to the Westerosi lords (who I believe GRRM intended to find out about Jon on a larger scale) - as far as SHE knows, he is the only hope of continuing the Targaryen line. She believes she can't have children. So if she cared about the Targaryen line, she should step aside and let him carry it on. But I don't think she will. I don't think she's capable of it. She's too convinced of her own specialness, of her position as a savior.
I'd love to see the Doom of Valyria too. The Targaryens weren't even a particularly large or important house in Valyria, one of the smaller dragonriding houses. So what did it look like in its prime? How big were their dragons? What happened?