Jon will struggle with his Targaryen identity.
If Jon's pep talk to Theon in the season seven finale proves anything, it's that he understands the struggle of juggling multiple identities. But going from Stark bastard to true-born Targaryen is a lot to take in, especially when considering the implications of Jon's claim to the throne. Jon is sure to brood over this revelation and struggle with who to share the news with and how, and he will also feel conflicted about his romantic relationship with his (now-known) Aunt Daenerys. Expect this struggle to be one of the main focuses of season eight.