In the classic series, male Time Lords regenerated into male Time Lords. Female Time Lords regenerated into female Time Lords. We for instance met 4 versions of Borusa, ultimately as President of the Time Lords, but every time he was male. We met 2 Romanas, both female. The Master - always male. The Rani - well, we only saw 1 version of her.
There was never a comment, whisper, or hint that they could change until the new series as noted above.
But... It's done now... and I think ultimately I'd rather sit through 2-3 years of a female Doctor, in order to get to a new Doctor, than to turn off, and see the series potentially face the axe, again, and be without ANY WHO for god-knows how long... who knows... maybe I may just like her.