Doctor Who Theories?

Obviously Davros is back and it looks as if the Tardis is a paradox machine once again, which means it's in danger. Donna has promised to travel with the doctor forever and has shown intelligence and compion to aid the doctor. I'm betting that somehow she becomes part of the tardis itself in order to save it. In Turn Left the fortune teller was afraid of Donna's power, stating 'who are you, what will you become'? and people were implying that the universe bends around her-could that indicate the time vortex?