First off, I'd like to see Doc for one more year. I think this team can be competitive (and is built to be competitive with its current salary structure) for another year, and for the sake of continuity, I think Doc is the guy to do it.
Second, I'm not sure who should be coach after Doc, but am pretty sure it won't be Adelman based on age alone. IMO, it really depends on where the team stands in the summer of 2012.