I've seen what happens, but I won't say what happens. Spoilers.
Anyway, there's a Doctor Who/cat macro community on LiveJournal (
http://community.livejournal.com/ihasatardis) where some people now and then talk about who they think the next actor to play the Doctor should be (in a perfect world, I guess). I saw Alan Rickman, James Spader (recent), Bill Nighy (earlier and recently), and others that I can't remember and don't remember how far back to go to find.