The lackluster box office for Knight and Day may lead to Mission: Impossible IV being reworked or maybe even scrapped altogether.
I doubt that. The Mission: Impossible franchise is still a commodity for Paramount and I don't think they would do that to J.J. Abrams, who has been very good for Paramount so far.
On the topic at hand, I don't think Chris Columbus will direct any Superman movie. He just doesn't seem like the type that would jive with the likes of Christopher Nolan, whom I am assuming would have some say as to who steps into the director's chair.