Extremely premature thoughts assuming Peter Capaldi IS the 12th Doctor...
I think that would mean they are going to attempt to return to the original format, where the Doctor is an old, cranky, antihero type. A lot of people would like to see that, which is why Hugh Laurie gets mentioned so often. Greg House is basically the 1st Doctor. Capaldi is best known for playing that type of character. Capaldi's face even LOOKS like a strange cross between Hugh Laurie and Peter Cushing IMO haha.
Making such a move would be BOLD, because the mandate for Doctor Who CLEARLY is to be children's show as defined by modern parameters. They pretty much NEVER have given the show much of a hard edge since the 2005 return. I don't know how they can square the two. For Capaldi to be successful Doctor, the show would have to stop being made for children.