Well, I'm going to join the chorus of 'why kick Craig out of the role now, he seems to be doing well, and Idris is almost the same age anyway'.
As for a black bond, eh, no problem with that, though I seriously doubt it'll happen any time soon, there aren't even that many movies that get released with a black protagonist that aren't about black-culture or starring Will Smith (and any other minorities stand even less of a chance). So taking a beloved white character and making him black would probably cause your producer to kick you in the nuts.
Also
Programmed_For_Damage said:
As to whether a black actor can play Bond; sure, if a white actor can play Shaft. However I think if a character is written in a series as belonging to a certain gender/ethnicity then they should probably be played by an actor who best matches that description, purely for accuracy to the text. I was horrified at the "white-washing" of movies like Avatar and potentially what's happening with Akira. They should have definately been played by Asian actors. It's not like there aren't fine Asian actors. There are also a lot of excellent black actors, case and point Morgan Freeman, however I was surprised when he was cast as Colonel Kurtz in the movie adaptation of Stephen King's 'Dreamcatcher'. Kurtz in the novel was a tall, fair haired, albinoid white guy. He was only a minor character so it's not a big deal, but as I was very familiar with the story it just seemed a bit strange. Presumably he was hired to bring some credibility to the movie.
Then again I have no problem with a black Spiderman, and I'm a Spiderman fan. I guess because Spiderman's identity has very little to do with his ethnicity.
Speaking of racial swaps, Morgan Freeman and Stephen King, they changed the ethnicity of Red in the Shawshank Redemption film. Red in the novel was actually white-Irish, and had ginger hair, hence the name. In the film they cast Morgan Freeman and it worked perfectly, he nailed the role and was a major contributor to that film's awesomeness.
Really it's more about who works with the role, like Idris Elba was quoted as saying above, it shouldn't be about having a Black Bond, it should be about having the best Bond (regardless of ethnicity). Though, as I said above, the best bond will be judged as the one that moves the most tickets, and either due to hollywood's mistaken perception of the public's racism, or our actual racism, I don't think they'd risk putting anyone not white in the role.
Edit: Yay questions!
If Idris Elba actually does turn out to be the next Bond, how would you feel? Fine, he's a perfectly capable actor, though I don't care that much about Bond so probably wouldn't see the new film anyway.
Do you think James Bond is a role that only white guys should play? No
How would you feel about an asian James Bond? Again, fine, unless they got George Takei to play Bond, then it would be the best film ever.
Do you think there are certain roles that shouldn't be open to everyone? Well, anyone based on a real person for a start. People in historic settings should be suited to the setting or at least explain how they got there (e.g. it would've been weird if in the Last Samurai Tom Cruise just started as a samurai and it was never addressed). Any fictional characters are fair game though.