fictional character, the moment when that character starts being portrayed by a diverse group of actors is the moment that character becomes a true part of the culture. See, Martin Luther King, Jr was an actual person, Bond is a fictional character. Fleming's original time and historical context is long past. The films have no chosen, as they could have done, to remain set in the Fleming era instead they have moved forward along that timeline and are always set in 'present day'. Perhaps the leading reason for that is that a major feature of Bond films and Bond himself is cutting edge technologies, he's not the past, he's a step ahead. Today's Bond has to have tech we don't have, but obviously the man needs a cell phone, Fleming never even dreamed to give him such a thing.
If he's going to live in the present, his attitudes and those of the universe he lives in must also be in the present. In Fleming's time, M would not have been a woman, but in the films Judy sure is fine in the role, and a woman in that job makes full and reasonable sense. So in terms of casting and Fleming's 'intent' the bridge has been crossed long since.
In what world, fictional or real, is M a woman but no double 0 agent is black? Because I'd have to contend that in Fleming's Bond universe, the dynamic between men and women and the expected gender roles play a far larger part in defining that universe than racial dynamics or identity, so once you have make women Bond's equals and superiors, Fleming's world has been updated drastically and is no longer Fleming's world.
Idris Elba would be a most excellent casting choice for the role of James Bond.