Of course, this is all based on one version of real world succession rules. Game of Thrones has never fully explained the rules of succession in Westeros, and it has been established in the show that many characters believed Robert was a usurper even after he became king. These people are devoted to the idea that the Targaryen line is the one and only true dynasty, and they would surely support Jon's claim. So, while Cersei may be within her rights to sit on the Iron Throne, there's no denying House Targaryen is destined to rise again. The real question is if Daenerys will be able to live with the knowledge that Jon has a better claim to the throne than she does, or if her newfound family member and lover will be seen as a threat to her power when the Great War ends.
