Note: I'm not asking if you think that there *should* be a female Doctor. One could like the idea, but not necessarily think that it would work on TV or should be done.
I'd be okay
with a female Doctor. Part of me even wants
to see one. But at the same time, it would be SO EASY to mess up. And I worry that it would hurt the show's ratings. Though like I said, I don't really care about the people who would quit watching the show just because they made the Doctor female...but it could hurt the ratings, and that would be bad.
I would rather have the Doctor played by a black actor the next time. I think that could work, and the Doctor has already said that he can change skin-color, and isn't always white (in "The Sarah Jane Adventures: The Death of the Doctor pt2")...though that might pose some issues when the Doctor traveled to a time/place in the past where race was an issue. Though I think the producers would probably just ignore it (just like they ignore how odd Jenny & Vastra & Strax would be in Victorian London) - but it could make for some compelling stories if they didn't ignore it. Then again, it could also make for some preachy and cringe-worthy stories if they did make it an issue. But I think that's just a challenge, and not a reason never to have a black Doctor.
But I guess you could say the same about a female Doctor being a challenge - so I would be totally okay if the next Doctor is female.