Whoopi Goldberg for the Doctor. Let's cover all the bases. Well, most of them.
Well... I'm thinking more the lines of Sophie Okonedo.
Not that I expect 100% that they'll change the Doctor's ethnicity and gender when Matt Smith leaves. But there were some pretty loud grumbles when Paterson Joseph (whoever he is - I just know him as a fleeting guest star who played an a-hole in an Eccleston episode) was allegedly "passed over" as the 11th Doctor (even though by all accounts he may never have been in the running), and ever since Neil Gaiman established that
some Time Lords can change sex, and RTD had the Doctor affirm in Death of the Doctor that a skin color change is possible, everyone's just been assuming that the Twelfth Doctor is going to be odd man (or woman) out from the rest...
And lest you think I'm pushing the thread on a tangent, if Yates ever does make his movie, the same pressures will apply (perhaps even stronger if the BBC
doesn't cast a non-Caucasian or a woman for the part in the meantime).
Personally, I don't care. As long as a) the change of gender is part of a storyline and not considered "normal" for some Time Lords because I refuse to accept that a future incarnation of Romana or Susan could conceivably look like Ron Jeremy

and b) whoever they cast is truly the best choice for the role.
Alex