Ummmm... no. That is a rather broad interpretation. A subsequent development would be Stephen King writing another book. If all it takes to to be a sequel is a subsequent development, every bit of fan fiction ever written is a sequel. There is only one author of the series. He writes the books. He might provide the rights for people to make movies of his works, but he retains the right to do the next book, i.e. continue the story. Anything based on something written by someone else, is not a sequel. Sorry. My standards of fiction are simply the same as the copyright.
P.S.
By your logic, we have seen sequels (MANY OF THEM) to Children of the Corn, Pet Semetary, etc.I don't believe any of us think of those as sequels either.
there's a difference here. king didn't really have anything to do with those sequels. he's directly involved in promoting this movie. so that lends it the weight of canon, regardless of whether he wrote it. he didn't write all the comic book stories either, but he had input and some kind of involvement, correct?
jj abrams may be ok at some things, but i'm angry at hollywood for allowing him to get his hands on both star trek and star wars. laziest, crappiest additions to both universes. he made mindless popcorn flicks and slapped the franchise names on them.
regarding dark tower, i'm hoping the same doesn't happen to them, but idris elba's casting ranks pretty much dead last on my list of concerns. appearances aren't a problem. spirit of the story is. and while detta and roland had their subplot about racism, it wasn't the most important plot point in the book by any means, so getting so hung up on it is a bit weird to me. there are multiple ways around it. there was never going to be a spot on adaptation of the dark tower. harry potter had 8 films (a major accomplishment for a book series to begin with) and they had to leave things out too.
