Yeah. While I like the idea of Capaldi as the Doctor, I have a really hard time picturing how Clara's relationship with the 11th Doctor will translate once he regenerates. So much of Clara's interactions with the 11th Doctor is based on this sort of casual flirtation with each other that I'm not sure makes sense with an older Doctor. (Unless Capaldi turns out to be a suave, sexy older Doctor like Jon Pertwee.)
It would be funny if he pointed out to her, "You know, no matter what face I have, there's still an 1100 year age difference between us."