President of programming Casey Bloys says the final season will not air in theaters — and he won't try to launch one of the four (maybe five) "successor shows" on the back of the remaining six episodes.

While the end of the road for Game of Thrones is in sight, HBO is by no means walking away from its storied franchise.

When the fantasy drama based on George R.R. Martin's best-sellers returns July 16 for season seven, it will have 13 episodes remaining, with seven this year and the remaining six either in 2018 or 2019. Then it's up to HBO's development pipeline to see if one of the four (possibly five) prequel series comes in strong enough to move forward after the rightful heir to the Iron Throne is finally revealed.

In an unprecedented move, HBO announced May 4 that it is teaming with Max Borenstein (Kong: Skull Island), Jane Goldman (Kick-Ass), Brian Helgeland (Legend) and Carly Wray (The Leftovers) to develop what Martin calls four separate (potential) "successor shows." Martin is involved in all four, co-writing at least two of them. Thrones showrunners David Benioff and Dan Weiss, meanwhile, opted to remain on the sidelines and will forgo executive producer credit on a potential prequel in favor of focusing on the final two seasons and, after a decade-plus, stepping away from the world of Westeros.

"I truly think it will go down as one of the best shows in the history of television," HBO president of programming Casey Bloys tells The Hollywood Reporter. "It will be insane for a network not to at least entertain the idea of a successor show."

Should a spin-off from the two-time Emmy-winning drama move forward, it would be the first time that HBO has revisited one of its iconic series. And Game of Thrones makes the most sense: It's HBO's most-watched show in history with an average gross audience of 25.7 million viewers. "It's easily a multibillion-dollar brand," says Henry Schafer, exec vp at branding specialist Q Scores. "Given all the TV fragmentation, it's a great brand to help hold on to their subscribers. Game of Thrones is the No. 1 audience-engaging show on cable television right now."

All four prequel ideas are in their infancy; Bloys hasn't so much as seen an outline yet, let alone a script. Few details are known about the various projects, but Bloys did confirm that all of them are prequels that will be populated with entirely new characters. The executive has no plans to dilute the franchise or piggyback off the final season and rush the next potential chapter. Also off the table is a popular theory that the cabler might air the final season — which could consist of all theatrical-length episodes — anywhere other than on HBO. "This is for subscribers," Bloys stresses.

Still, HBO remains optimistic that one of the four will come close to the quality of the flagship and help extend the franchise's life, though Bloys wouldn't rule out going back to the table again should none of them work out. And if all of them are strong? "That's a high-class problem that I'll solve when it comes to that," he says with a laugh. "It would be nice if we got one of these off the ground and it ran for multiple seasons. The nice thing about George's universe is it's so vast. So could you do another one after that? Sure."

In the meantime, HBO has been busy ramping up an impressive drama slate that includes Westworld (its highest-rated freshman series, returning in 2018); David Simon's James Franco porn drama The Deuce (Sept. 10); J.J. Abrams and Misha Green's Lovecraft Country; Alan Ball's untitled family drama starring Tim Robbins and Holly Hunter; and Damon Lindelof's buzzy Watchmen take, among others.

"It would be nice to have a Game of Thrones property, but the fate of the network does not hang in the balance," Bloys says. And as for just when the final season will air? Bloys defers to Benioff and Weiss, who are busy writing and prepping the production schedule for the globe-trotting series.

Below, Bloys opens up about all things Thrones.

You've only got 13 more episodes at this point. Does Thrones tell a complete story? Do you already know how it ends?

Well let's put it this way, the guys know very well the story that they want to tell. They have had a good idea of how they want to end their story for a very long time, so we're just excited to have them do that.

The original idea was 15 more episodes, and now you're getting two fewer. What happened?

There was never ever really a set plan. I think, honestly, some things kind of leaked in the press or may have been said here or there. They had an idea of where they wanted the arc to go, but in terms of the number of episodes, the number or the length of episodes, that has never been a hard number. I imagine the story is dictating for them how many episodes is right for them.

You've announced six more episodes for the final season, and there's no airdate time frame. Given what you know about the pace of production and working with Benioff and Weiss, is it likely 2018 or 2019?

I can't really speculate on that. All I will tell you is it is obviously a very ambitious season. This is the culmination of eight seasons of fantastic storytelling. They are writing, and they need to look at the production schedule, and we will take their lead in terms of the airdate that works best for them. They don't even know; they are still putting the season together. And as you can imagine, it's a very complicated show to produce, so it's not like putting together a production schedule for a sitcom that shoots on the stage. It shoots all over the world and takes a long time to figure out where, when and how to shoot. So they're in the process of doing that, and they'll let us know.

Have you kicked the tires about how the final six episodes could air? Could they be weekly? Could you space them out and split them like Mad Men's final season?

We haven't gotten into to the airing plans. I don't anticipate anything totally unusual, but again, until we figure out the production schedule, everything is going to come from that.

Would you rule out airing in theaters? Or having some kind of theatrical release, maybe Imax?

I would. This is for subscribers.

This is the first time HBO is revisiting one of its originals. How did the idea for these successor shows come about? Was this an organic decision or did pitches start coming in out of the woodwork?

I consider us incredibly fortunate to have a show that this many people have such interest in and that is such a good show. Truly I think it will go down as one of the best shows in the history of television. It would be insane for a network not to at least entertain the idea of a successor shows — I was going to say "prequel" but they're not spin-offs because there are no existing characters going off the flagship. It's not Laverne & Shirley from Happy Days; they are prequels. But it would be insane — with a universe like George has created that is so vast and has so many characters and so many timelines — to not, at least, entertain the idea, which is what we're doing.

George has said there's a fifth one in the works. Who is the writer?

I have a deal for four spinoffs right now with four writers.

You're taking a highly unusual development path with these; it's rare to develop four properties at the same time. Why go this route?

This franchise is really rich and very exciting. It is going to be really, really hard for anybody to match the level that this show has set in terms of quality and filmmaking. So the idea was, if we're going to try it, let's take a couple of shots and see. My hope is at least one lives up to the level of quality Benioff and Weiss have set. But again, it's also very early in the process. I haven't even seen an outline for them. The priority here is obviously season seven and then season eight. You're not going to see a situation where we're launching a prequel on the back of the final season. The final season is going to be its own event. It's going to be a big deal for us and the fans. I'm not interested in using it to launch any other show. We mentioned the spin-offs because obviously there's a lot of interest in them, but it's a very embryonic process, and you know how development goes — it can be a long process. We confirmed their existence because there was a lot of interest, but it's not something that we are fast-tracking to get done to air immediately after the final season. I'm guessing fans will need some time to decompress from how amazing the final season is.

If these outlines and these scripts come in, can you see one of these prequels airing before the final season?

No, absolutely not. No way. There's not going to be anything — the only thing that will be Game of Thrones related on the air will be season seven and season eight, and then it will be a good long while if and before anything [new] gets on the air. Again, I say that only because I think when we confirmed the [prequels'] existence — that we were exploring this — that read to the general public that, "Wow, these are far along." We were just confirming it so people didn't speculate.

You've said before HBO is not going to have a version of Game of Thrones on in every quarter — which is a strategy AMC is doing with The Walking Dead and Fear the Walking Dead. But in success, what happens if three of the four come in great?

You know the odds in development. I think that is probably unlikely. I was at Touchstone during Who Wants to Be a Millionaire. They had a hit show and they aired four in a week. This show is very special. I'm not looking to have as many as possible. My sense right now is we would be very lucky if one of the four rises to the level that we have set. Now, theoretically, what if they're all great? That's a high-class problem that I'll solve when it comes to that. But knowing what we know about the development process, that's why we wanted to increase our odds. But I do not see a scenario where we have more than one. But again, high-class problem.

This is such a sprawling world in terms of timelines, mythology and characters. How much trepidation do you feel starting over from scratch? These are all prequels and as you've said, completely separate from the successful world you've already built.

Doing any show, any pilot, any potential series is very difficult — it's lightning in a bottle. There's a little bit of magic, a little bit of luck. Even with the best of scripts, it has to be cast just so, it has to be directed just so, written just so. In the best case scenario, it's difficult to get the show right. What you've got in this situation is probably one of the best shows in television history as a benchmark. That makes it that much harder. We have world-class writers taking shots at this. I'm hopeful, but the fans have come to expect a really high level of writing, acting and storytelling, so it's a high bar, no question.

Considering all of the projects are prequels, will these be more along the lines of Fear the Walking Dead — which exists in the same universe but does not have any direct connection to the flagship — or Better Call Saul, which will eventually take viewers to the beginning of Breaking Bad? Could these eventually connect to a flagship or will they be in an island of one?

The whole world is connected to some extent family tree-wise, and the timelines are so vast that unless you jumped ahead tens or hundreds of years, I don't see [the prequels connecting] happening. The other point I want to make about clamping down spin-off fever is if none of them work, remember, we are building up our drama slate: We have Westworld, which is our highest-rated freshman drama in history; Watchmen, which we're very hopeful that Damon Lindelof is excited about working on that; we've got Lovecraft Country; Alan Ball's show; we've got David Simon's new show. So it would be nice to have a Game of Thrones property, but the fate of the network does not hang in the balance.

If you were to look, say, 10 years into the future, what's the state of Game of Thrones on HBO?

Going back to that Who Wants to Be a Millionaire comparison, I think overdoing it — like having multiple shows — there's a risk of diluting the quality and driving it into the ground. I have no interest in doing that. But it would be nice if we got one of these off the ground and it ran for multiple seasons. The nice thing about George's universe is it's so vast. Could you do another one after that? Sure. By the way, in 10 years, I'm guessing that will be someone else's problem! (Laughs.)

How involved is George in all of these?

He's co-writing two of them. A lot of it will depend on how much George is engaged and how he clicks with writers and how much the writers want to bring him into the process. That will vary project by project. But he's a fantastic resource. Nobody knows the universe better than the one who created it.

Will Weiss and Benioff be credited as exec producers even though they want to walk away from the franchise after the flagship ends?

In theory, they are entitled to passive participation as a sign of respect for what they've done with the franchise. By the time the eighth season airs, they will have been with this show for 13 years. And I think it's important to point out this is the only thing they've worked on. They haven't gone out and pitched other TV shows or movies. This is an all-consuming job, and they want to see it through. When they're done, they don't want to feel any sense of responsibility or obligation, and they said to me they hope to watch whatever spin-off they have purely as a fan, sitting at home, not overseas working on a production. So I understand that they need a clean break. They've done something historic and huge and they don't want to feel obligated to participate or offer any guidance to a show.

Will they have any say in terms of what moves forward, if anything?

They don't want any. They want to focus on, at this point, season eight. I don't think they want to be distracted by somebody else's writing that they're not responsible for. They have said that 13 years is enough.

On the flipside, what happens if you're not impressed with any of the four prequels? Would you try again?

Maybe. I don't know, it's hard to say. We've got some really amazing writers so I'm hopeful. It would be nice to find something else there. HBO will survive with or without a prequel. But that said, the world is so rich, it'd be great if we could crack one.

Considering the scope of this world and the volume of characters, have you considered doing something like a prequel anthology where it's either a different character every season or every episode, a la Black Mirror?

No. I want to be mindful of overdoing it. I look at this universe as very precious resource. I do not want to overexploit it.

Game of Thrones returns Sunday at 9 p.m. on HBO. Bookmark THR.com/GameOfThrones for theories, news, interviews and more.