Regarding that last post, I note a particular thread of comment. Here's the first one:
No, please - look, I know that the sex/race swap thing has creeped into the Doctor Who Hive Mind over the last decade or so - and when you're talking about a show with a thousand year old man flying around the universe in his magic phone booth, there's no logical reason why you should be able to do something as simple as flip a chromosome or tweak the skin color - but I don't like the the idea.
You wouldn't make James Bond a chick, would you? Or a black dude? How about Sherlock Holmes? They should just leave the Doctor as an English (or occasionally Scottish) white dude.
Every time a prominent character in pop culture has his race switched, this comes up. Some folks say it's offensive political correctness, and other folks call those folks racists. Who's right? It depends on whether it is offensive political correctness. Casting a black actor because you want to pander to people who think it's progressive is stupid and offensive. When the best actor who auditions for the job is black, casting him is the only reasonable thing to do.
The only time an actor's race should matter is when the script calls for the sociology of race to be an issue. So Othello, for example, should usually be chosen based on race.* But Bond? Unless you intend to do a self-aware revisionist Bond movie that comments on the sex and class assumptions of the Fleming stories, why the hell _not_ a black or female Bond? And for that matter, you can use a black or female actor to lampshade those themes or play it straight and focus on what makes Bond awesome without fixating on -isms. I've never felt the need to see a Bond movie in the theater, but if the next one stars Isaiah Mustafa or, say, an actress who can pull off a vibe like Jenette Goldstein's Vasquez in Aliens? I'll show up opening night.
Sherlock Holmes, though, is another story. Sherlock Holmes shouldn't be played by a black actor, because Robert Downey, Jr. is not black.
[* - And even then, it's not certain that he should be black--just that he should be a race apart in an otherwise unicolored environment. Patrick Stewart played Othello against an otherwise all-black cast, which is brilliant. Being the only white character in a black setting isn't identical to being the only black character in a white setting, but the differences between those scenarios can say interesting things about both.]