3. Under The Dome (2009)
Why It Should Be A Movie...Under The Dome is typical King in its set-up: an ordinary town come up against a mysterious force and have no choice it face up against it. In this case, we find out what happens when a huge, invisible dome cuts of the town of Chester's Mill. It doesn't matter
why it happens, simply that it does, because King uses this idea to explore America as a microcosm of itself. Though the book is certainly long, it would make for a great, high-concept ensemble thriller, one that the likes of M. Night Shyamalan might've helmed with success once upon a time...
Why It Never Will Be... It's currently airing as a TV series over an CBS, and although the show is pretty good, the storyline will inevitably find itself stretched out beyond all recognition, to the point where it no longer resembles the words written in King's book. Though that's fine, the fact that we have this TV series means that we probably won't ever get a movie adaptation. And one of the best things about the original novel was that the dome only covers Chester's Mill for a week - the point was in how quality things can escalate when humans are cut off from the world.