Idris Elba at this point wouldn't be a good fit simply due to his age. It would be odd to do a reboot with someone his age.
That being said, if they did a one or two film stint about an older Bond I would absolutely watch it. Elba is an outstanding actor.
007 as a woman, no.
007 as a black British man? Why the hell not. Most characters from older book series are white. Hell, Red was white in the writings adapted to Shawshank. Morgan Freeman was Red. Couldn't imagine anyone else.