Bit weird to word the thread title, opening post, and poll as though she had actually been announced as the companion, when in actual fact it's just a random assumption based on the fact that she posed for a photo with Capaldi on set, which as others have pointed out has happened with other past cast members.
Probably would have been better worded as 'Could Jenny be the next companion'.
Anyway, I doubt it will be her (especially with other posters above pointing out that the photo in question is actually quite old), but if there were any chance of it, i'd quite like the idea. Would be interesting to see the doctor travelling with a character who is a timelord, but at the same time has the naivety of a human, and is also his daughter.
As I say, I doubt it though. I think they'd much more likely go with someone new, than try to sell 'hey everyone, remember that one episode character from seven years ago' to the mainstream audience.