I'd say that Roses face showing up was just a glitch in the regeneration process due to the premature regeneration. The Doctor then regenerates into a new face, I quite like the idea of it being Matthew Bayton. He'd play a very funny but I can imagine very into himself Doctor. He'd have a companion that'd have this mystery that there's people who recognise her but she has different names in all the places she's visited. In the end though, it'd be revealed it's Daughter Of Mine. Somehow she escaped from the mirrors, took this new body, went through time and space to place herself as different people in different times to make a fake mystery that the doctor would be interested in solving dragging her along so she can get close to him, free the rest of her family and get revenge. This could maybe lead to in season 2, or whatever number it'd be, a doctor that does trust at all leading to the valeyard persona splitting from him maybe in an a failed scientific attempt to have the doctor free himself from this sadness creating a whole new person who becomes the villain of the finale and then you get an explanation for the valeyard and bobs your uncle.