Matt Smith still is The Doctor for the time (as relative as that is) being so there's no need to cry (yet). He did send us Whovians a message through BBC's Who page earlier today.
"Doctor Who has been the most brilliant experience for me as an actor and a bloke, and that largely is down to the cast, crew and fans of the show. I'm incredibly grateful to all the cast and crew who work tirelessly every day, to realise all the elements of the show and deliver Doctor Who to the audience. Many of them have become good friends and I'm incredibly proud of what we have achieved over the last four years....
The fans of Doctor Who around the world are unlike any other; they dress up, shout louder, know more about the history of the show (and speculate more about the future of the show) in a way that I've never seen before, your dedication is truly remarkable. Thank you so very much for supporting my incarnation of the Time Lord, number Eleven, who I might add is not done yet, I'm back for the 50th anniversary and the Christmas special!
It's been an honour to play this part, to follow the legacy of brilliant actors, and helm the TARDIS for a spell with 'the ginger, the nose and the impossible one'. But when ya gotta go, ya gotta go and Trenzalore calls. Thank you guys. Matt."
So let's run with nothing more than hopes and dreams and conjecture.
Personally I'd love to see some weird wibbly-wobbly timey-wimey stuff and see my favorite companion return as an empowered Doctor - Billie Piper. I have to admit... I started to tear up a little just searching for this gif.
When I posted the Who question on my facebook page - C.S. Muncy (occasional ComicBook.com photog) said - Tilda Swinton - whom I actually think would be genius in the role and would be fun as heck to listen to her do Moffat's dialogue. Bonus feature for Tilda is that she's got the hair for the role.
Ok, now let's get a bit serious here - as much as the Who series, especially under the control of Moffat has broken a lot of ground on characters when it comes to their sexuality, species, etc... I think that the next Doctor is almost certainly going to be a guy. Matt Smith, earlier this year was quoted as saying, "“I think there will need to be a younger, cooler person than me. Or maybe an older, cooler person, who knows?” So... um, ok. I doubt it will be someone dramatically older than Matt Smith so let's discuss the possibilities here.
Number one being Martin Freeman. People over at BBC casting seem to think that Matt Smith and Freeman are relatively interchangeable as both were in close contention for the role of Watson on the BBC series Sherlock. Freeman also has quite a following within the sci-fi world being in The Hobbit, Hitchhikers Guide to the Galaxy and briefly in Shaun of the Dead. He's fine with a talking robot sidekick so if K-9 ever returns again they'll be fine there. But unfortunately he's quite a bit booked. Between The Hobbit trilogy to finish, he's still on Sherlock (whenever the heck that returns again) and three other films currently in different stages of production just this year alone. Though 2014 is seemingly open...
Number two, considerably less likely is Ewan McGregor. To my knowledge there's never been a big name star play a Doctor (usually they become famous because of the role) but hey - can't you see the Doctor doing something like this?
Equally un-likely as with Freeman and McGregor he's a bit busy at the moment - Idris Elba. Again quite a sci-fi/comics actor - he's currently starring in Pacific Rim, and has been in Thor, Prometheus, and (unfortunately) Ghost Rider: Spirit of Vengeance. People are also talking about him taking over the James Bond franchise after Daniel Craig ends his run.
Since the Doctor seems to keep getting younger with each regeneration (in the current series at least) the actor will likely have to be around the same age as Matt Smith, which unfortunately rules out a lot of the people that that internet likes for him - but here are my two contenders (special thanks to reddit/r/DoctorWho)
Rupert Grint - from Harry Potter fame can do the awkward of Matt Smith knows the world of fantasy better than most and has a relatively free schedule. Also there seems to be quite a call for a ginger Doctor. Grint would also bring a large number of fans with him over from the Harry Potter series - which would be good for ratings.
Finally - and who I think is probably the best possibility is Russell Tovey. He's relatively unknown (at least in the U.S.), but has enough experience to fill a main role, has a quirky look (dear lord, look at those ears) which would follow along the Matt Smith lines. There's also the sci-fi world background - Being Human just ended, where he played a werewolf - Being Human was a BBC series as well...to which the showrunner is also an occasional writer of Doctor Who. With Moffat dropping occasional hints that he might be thinking about leaving, we might see a bigger change in the series than even just a regeneration.
But who knows? This is the Doctor we're talking about... anything can happen.
Who would you want to see as the next Doctor? Leave your thoughts in the comments!