2. A Running Gag That The Doctor Doesn't Speak French
This one seems like a bit of a stretch to speculate, but hear me out on this. The other day,
Doctor Who Magazine posted a few pages of the script the BBC used to audition the potential actors for the role. You can read all three
here. In one of the scenes, fresh from his regeneration, he confesses to Clara that he's accidentally deleted French, and since Ten used to shout French all time, this seems primed for a great running joke.
THE DOCTOR: Ive deleted French! Plus all cookery skills, and the breast stroke. And hopping. Never mind hopping, who needs to hop. Ohh, the kidneys are interesting. Never had that before interesting kidneys.
Brilliant. Now, I think that that could potentially be a pretty funny running gag, to have a Doctor who has to explain time and time again, "No, I don't/can't speak French!" (Even though the TARDIS matrix translates it, but hey.)