As the story is already finished the producers won't have the same problem as the creators of the GoT tv show. The most important thing now is the casting. I'm very afraid they will make the same mistakes as they did with Warcraft and Legend of the Seeker. I hope the casting directors realise that they are only a couple of very beautiful people in the books like Lanfear, Berelain and Galad. That they won't do a "Saved by the bell"esque teenagers casting. Just hire the same people who did the casting for Game of Thrones and I am at ease.