Elba has been thrown around so much the last few years but while the man is a fantastic dramatic actor I've yet to see anything to suggest he would suit the Doctor. Seems like he is just tossed out as the one well known and talented black British actor.
Not only do I think he isn't particularly well suited to the role, but I doubt he would take it as he already has an established and consistent TV and film career.
Most of the fan favorites are just as unlikely for similar reasons.
If you want to do some affirmative action casting though, why not consider a few other names?