Can it change much more?
I think if he left I would be just as curious at the changes made and I think the shows purpose is clear enough that it can't change too much, just as long as it isn't Americanised too much...
I'd go along with that. After all, Doctor Who has survived numerous changes of leadership - sometimes for the better, sometimes for the worse, but it's evened out overall. I'd agree, though, I hope it doesn't get too Americanised - there are plenty of American shows I love, but it wouldn't work in this case.