^ Well Moffat and Tennant at least have said how The Day of the Doctor moves the character forward. I wouldn't consider replacing the character with a different character to be moving the character forward, more like ending the character.
Also, it sounds like the Doctor confronts what he's been running from all of these years and it gives a new spin on his future adventures. Much less meaningful if he stops running and that's it and someone else takes over with his name.
So, I don't think that's going to happen. New set of regenerations, very possible. New character that assumes the persona of the Doctor, unlikely.