It’s that it’s looking like it will be the only show.
No dude, it isn’t. You keep saying this but it’s not true. They’re currently working on Season 3 of SNW and the concept of it ending after 5 seasons is pure speculation. They’re also currently working on two different Star Trek movies. They also were working on SNW long before it was announced because it takes time behind the scenes to write out the concept for a show, work on the idea, figure out the cast/crew and what not. The push for Legacy by fans is as intense as SNW but it took them almost two years to announce SNW because they had to make sure everything behind the scenes lined up.
There’s no reason to believe that it’s going to be the only show.