James Bond's history never changes, he's the same man always. Drinking heavily and womanizing aren't part of MI6 Training. Bond is a Orphan, whose parents died in a rock-climbing accident. He was raised by the state and the only thing important to him is the duty. That's it. The death of his wife, the one woman he ever loved, is integral to the character. No matter how it appears in any of the stories after that point, no matter WHAT, Bond never loves again. Never connects again. He is damaged goods. He knows his time is running out. He drinks, smokes, womanizes, because it won't be those things that get him. He won't live long enough ti die of liver failure. He is one man and even though most people are exposed to his timeline completely out of order, it's important to keep it as close as possible to the original stories. That's why a lot of movies that aren't based on Fleming's novels (see: Moonraker) really bug me.
The character happens to by white, and changing him to black serves no purpose. If you're going to change James Bond, you better have a good goddamn reason.
That said, Black MI6 agent? Absolutely works. But he can't just be Bond, he needs his own story to tell and his own reason for strapping on the tux.
