Updated with Casey Bloys statement on a possible prequel:
Bloys noted that a prequel seems more likely than a spin-off that uses existing characters. “A prequel feels like it has less pressure on it [than a spin-off],” he said “[Author George R.R. Martin’s history of Westeros] gives you areas in which to say to a writer, ‘If you were going to do this, then go flesh it out,’ and we’ll see what comes back. But I don’t feel any pressure that we have to have something.”
“The only thing we’re working out is how many episodes they want to do,” says Bloys when asked what’s holding up the official Season 8 green light. The exec added that he “hopes” Benioff and Weiss will deliver more than six episodes.
“They’re still figuring it out because I think they’re trying to get a shape of the season,” he continues. “They always do what they think [will yield] the best version of the show. It’s all about how many they’re comfortable [with]. But I’ll always take more.”