Same thing that the Vikes got from firing CHildress. Giving someone you want to consider for the job next year some experience and a chance to show what he can do.
I doubt seriously that they're going to keep the running backs coach on as the permanent head coach. My bet is that they'll go with someone like Leslie Frazier or Don Capers.
I'm a semester away from achieving this milestone, but I'll ask you, oh mighty psychic: will I ever graduate college since I've been in school now off and on for ten years?