George RR Martin takes all his events from events of history/literature (red wedding(Black Dinner, scottish history), Frey eating pie made out of his sons (Titus Andronicus), etc.). I bet he'll do like Henry Tudor did to end the War of the Roses: he married the heiress of the House of York (Elizabeth of York) and unified the Houses of Lancaster and of York through marriage. Jon and Daenerys will do the same, and they've hinted at this in this episode will all the crap about Daenerys having to ditch her lover to have a political marriage in Westeros. Also, Jon is a Targaryen, and the Targaryens have a history of incestual marriages to keep the bloodline within the family.
Also, who else would she marry? Jamie? I doubt it, he killed her father. Euron? Na, Littlefinger? LOL
There's only Jon left.