To be honest I think it wouldn't work. From what I've seen of him I'm not entirely sure he'd fit the character. As for the whole "But he's black!" thing, I think its stupid when they do a massive overhaul of ANY character. Deadpool in X-men origins for example, taking the character whose known for being a wise cracking ********, and then making him mute was one of the dumbest things I've seen marvel do in a while. Same with Making Thor, a norse god, a woman, also a dumb idea. It'd certainly be an interesting idea of having Idris play him, but it'd honest just stir up more controversy than its worth.
My final point: FOR THE LOVE OF GOD DONT MAKE BECKHAM THE NEXT BOND!