The show runner for the TV series based on Stephen King's story, 'The Mist' has clarified (a bit) how they're expanding the story;
So the question becomes do you leave it, say that it’s already been done, or do you allow yourself to take the source material and reimagine it but staying true to Mr. King’s vision? I chose the latter. It is not the same story as in the book and the movie, nor is it the same characters – but fans of the story will still see clear parallels. I’ve compared it to the way they approached adapting Fargo, not in terms of content, but in how they played with the original material. Some things are exactly the same, some are totally different. Some things you think are the same as in the original, but turn out to be something else entirely. Some things you think make no sense at first but end up tying into the original story.