According to the books, there's another Aegon (the surviving son of rhaegar from his previous marriage to oberyn Martel's sister) who's also technically dany's nephew too. I like to see how this twist plays out. Though, since he hasn't been mentioned in the series I don't think he'll be shown. R. R Martin said the book and the series would have the same ending.
In as much, as Jon is the rightful heir to the iron throne I don't think he's personally interested in being on the iron throne...for three reasons, he's never wanted to rule...starting way back from castle black, 2ndly he has so much of a connection to the north than to dragonstone, King's landing or dorne, 3rdly, he has already pledged his allegiance to dany, Stark's are not none to break their words even if it means costing them their heads. Though, there's still the possibility of him leaving winterfell for Sansa but what happens to the Vale?... The knight's of the Vale came to his aid because of Sansa and they'll sure want to court her to be warden of the east in the absence of her aunt, her cousin is to dumb to be warden of the east. There's a lot of political web now around Jon especially now he's gone jiggy - jiggy with dany...though, targrayeans are known to wed each other in other to keep the bloodline pure. It's gonna get more complicated by the time he finds out his parentage. I think Ned Stark foresaw all this and tried to shield him away from the intrigues from an early age.