What do u think is going to happen in Series 5 of Doctor Who?

We already know of one companion that the Doctor is going to have in the future. He met her in the episode in the 'library' and she knew him, but he did not recognize her. She was from the future and was his companion in the future and remembered their time together, but to him, they had never met. She also had a sonic screwdriver that he had given her in the future. So at some point, she does become his companion and I'm thinking that it has to happen pretty soon so that the same actress can play the role before her looks change too much.