Yes - there should be one more. Just one though. They went a little crazy with Saw sequels. Not to mention Friday the 13th, Halloween, and Nightmare on Elm Streets. But one more intense, scary as fuck, turbo-psycho, foaming blood at the mouth, assault on the audience would definitely be welcome in my book. In fact, they should have a movie where Danny Boyle's zombies do battle with George Romero's zombies.