That's kind of scary! In my wishlist of writers for Series 9, I included Whithouse for a two-parter, and I also predicted that he would as well!
It's good news though, I've enjoyed all of his episodes so far. With all of his Being Human colleagues also working on the show, I'm now living in hope he may eventually succeed Moffat. He's always been my preferred candidate - he's written a contemporary story, historical stories, stories involving location filming and now a two-parter too. Combined with his experience of showrunning, and his fascinating approach of pitting sci-fi against faith (against Moffat's sci-fi against fantasy, and RTD's sci-fi against domestic drama) in a lot of his stories (School Reunion referred to childrens 'souls', God Complex is obvious, and Vampires and Mercy both had interesting undertones) I think he'd be great.
Series 9 is looking to be quite exciting!