Dr Who - Matt Smith's doctor

I was a bit saddened by the news yesterday evening when it emerged that Matt Smith would be leaving his tenure as the eleventh doctor. Dr Who has been the longest running UK sci-fi show on the television. Since the relaunch of the franchise it has been very successful. The three newest doctors have done well: Christopher Eccleston, David Tennant and Matt Smith. Each has filled the role in a unique and interesting way. Considering Matt is the youngest of the three I think he's done exceptionally well. He's been very entertaining.
But I can understand why actors don't want to retain the role for long periods - it can easily become all that they are known for. I guess some actors are happier with that situation than others. It's weird to think that an actor can be institutionalised in something that isn't real, I guess it becomes real for the actor and in many ways a part of their life. They are the character they play for the most obsessive fans.
I wonder how the role will affect Matt's life in years to come? And I wonder more about who will be found for the role next and what kind of a job they will make of it? It will be hard to live up to the previous incumbents.