Over at EW.com, executive producers D.B. Weiss and David Benioff gave a post-finale interview, offering up some of their concerns about moving forward with the series while author George R. R. Martin is still working on finishing the final two books, as well as their plans for adapting the very tricky, audience-unfriendly fourth and fifth books.
As far as Season 4 of the HBO series is concerned, fans need not worry. It will cover the rest of the third book, A Storm of Swords, and it's all been mostly mapped out. For A Feast For Crows and A Dance with Dragons however... things will get complicated; what with the two books containing overlapping timelines, and Crows specifically missing several key, fan-favorite characters. Add to that a long list of new characters and it could make for a mess. “The series has already reached a point where there are so many characters, particularly in Season 3 we’re introducing so many new ones, we run the risk of bursting at the seams as we try to cram every single subplot and all the various characters and it becomes impossible on a budgetary level and it becomes impossible on an episode-basis to jump around every few minutes to 30 different characters and locations," Benioff told EW, regarding the possibility of cutting future storylines. "We don’t want to do that, and recognize that as a real risk and we will take steps not to fall into that trap.” Weiss then added: "Time for negative population growth.”
The other issue here is Martin's books. If a new one isn't done in the next, say, three years the show will have run out of material to adapt. And while it's probably a good bet that Martin will get the next novel, Winds of Winter, out by then, he still has the final book to work on afterward. As a failsafe, Martin did tell Weiss and Benioff his overall plan for the story, but has also expressed that he'd be displeased if the show went on ahead of the books. "I don't think I'd be happy with that," Martin told EW. But for Weiss and Benioff, there are other things to consider.
“We can’t wait too long because of the kids,” Benioff said. “Issac’s [Hempsted Wright] voice is changing. Everyone is getting bigger. We have this wonderful cast, but we don’t have an infinite amount of time … We don’t want to become a show that outstays its welcome and tries to turn each book into three seasons. Part of what we love about these books and the show is this sense of momentum and building toward something. If we tried to turn this into a 10-season show we’d strangle the golden goose.”
Add to this the problems of future salary negotiations for the cast, whose initial contracts would have been completed, and even some cast members possibly wanting to move on to other projects potentially causing the recasting of pivotal characters, and you can see why Wiess and Benioff don't want to have the show go on for too long - and possibly can't afford to wait for Martin to finish his story in book form. Martin, citing the Spartacus prequel series Gods of the Arena, thinks that HBO can stall with prequel seasons of Game of Thrones or an adaptation of his Hedge Knight books, which take place in Westeros.
Even HBO programming president Michael Lombardo finally understands why GoT fans had concerns years back. "“I finally understand fans’ fear — which I didn’t a couple years ago: What if the storytelling catches up to the books?" he said. "Let’s all hope and pray that’s not going to be a problem”
So, as you can see, within a year or two, there's going to be a little bit of push and pull between the producers and Martin; with the producers wanting to keep the show, and the actors, on an affordable and set schedule and Martin thinking the series, and his other Westerosian content, can sprawl out for years and years. “We still have our fingers crossed that George will get there,” Weiss told EW. “That’s what’s best for us, it’s what’s best for the fans. We’ll cross that bridge when we get there.”
And then there's Martin, who still only predicting that the story will be over and done with by the seventh book. Mean, he could write an eighth. “I have a story to tell; the number of books is almost irrelevant,” he explained to EW. “I’ll do that in as many books as required. I’m still projecting it as seven.”