Top of my list would be Ejiro Evero if Denver elects not to keep him. (Why wouldn't they??)
Henderson has been spoken highly of, though he's never coordinated and this could backfilre.
An outide thought might be one of our former coaches, Aubrey Pleasant. He interviewed for a DC position with a number of teams, but lost his luster (and job) as a coach with the Lions. Currently consulting with the Packers.
Pure sentimentality would have me bring in Jerry Gray, also currently with the Packers as a backs coach, but has coordinated in the past..