as an old Whovian (i was a fan of the good doctor BEFORE i ever saw trek!), I'm not much suprised. when ecclestone backed out so quick, I was starting to wonder if the new series was gonna end before it got grooving. there was also, some time ago, a rumor that the next gen doctor would regenerate into a female form.
since they've allready shown what looks like an "x doctors" episode (with a guy that looks like a chunky version of Peter Davidson), there must be something up.
something to keep in mind is that the doctor is down to his last three regenerations. since he is the final living member of the Gallifreyan race, the old Whoniverse may die completely with his last regeneration (leaving only Torchwood behind)
let's hope The Doctor and The Master go out in a blaze of glory.