Game of Thrones is ending Sunday, but Netflix, Apple, Amazon and Showtime have all been "feverishly working to reconstruct the scale, acclaim, relevance and — not to be underestimated — subscriber-attracting properties of the HBO smash," says Steven Zeitchik. As one veteran TV executive put it, "There is an arms race going on for event television. There could be multiple winners. Or there could be no winners at all." Netflix has The Witcher, Showtime has Halo, Amazon is banking on a Lord of the Rings TV series, while Apple is finally giving life to Isaac Asimov’s sweeping Foundation. "The scramble isn’t happening just because the end of Thrones will leave a massive audience looking for their next epic (or, lately, a target for social-media outrage)," says Zeitchik. "For networks it’s about taking advantage of a new set of rules. Swords-and-scepters was once overlooked material — the stuff of a Tolkien adaptation in the movie theater every few years and, at best, a niche show on weekly television. Yet Thrones has turned in to the dragon that lays the golden eggs — it has averaged some 18 million viewers per episode this season, more than 50 percent above even the much-watched The Sopranos finale. HBO Now subscribers spiked by 91 percent during the seventh season. That success has changed how executives think, increasing the acceptable risks and price tags for a new genre series. (Budgets for a Thrones episode can now come in at more than $10 million, several times that of most high-end series.) Their logic is that not only is it worth making shows in categories like fantasy and science fiction — it’s worth spending a lot on them, too. Given how elusive a hit can be amid the present TV crowds, that means a lot of executives could soon be taking a bath. Consumers? They could be swimming in event-TV content." ALSO: Here are 15 shows vying to become the next Game of Thrones: From His Dark Materials to The Chronicles of Narnia.