Unfortunately, I knew that was bound to happen. The biggest clue is Moffat referring to Capaldi's first series being like Tom Bakers, which had Jon Pertwee's recurring in the first serial; Sarah Jane and UNIT, so I guessed that we'd have a few episodes with the detective trio.
Hopefully once Moffat leaves, the new producer will put the show back on track and ditch them. The Sontarans are like in the DW big five (Daleks, Cybermen, The Master, Sontarans and Weeping Angels), so having one as an ally really is a dumb thing to do. Plus it's so badly written. One thing I hate about DW in the last few years, especially in series 7 is that there is far too much humour in it. Crimson Horror is a prime example of this, and Dinosaurs on a Space Ship. Some people say that there's a dark side to Smith's doctor, but I really can't see that at all. They really need to sort out the show next year.