Matt Smith On How Long He'll Stay

In an interview with The Guardian Matt Smith was asked how long does he plan on staying in the role of the Doctor ( If it was me I would be sick of answering this question) his reply

"It depends on your physical and mental state at the end of every shoot. I just take it year by year, but I'm quite excited by the coming year – it's the 50th anniversary, which'll let us be even bigger and bolder than ever." It's harder to think how much bigger, bolder, stranger. Don't there come limits? "Never. Not in Doctor Who. That's the beauty of it. You're never bound by logic, or time, or genre, or space, or location, which is what makes it such an ingenious televisual conceit."

The only problem I see with that quote is that the 50th anniversary of Doctor Who isn't next year.  Does this mean that the next series goes on in 2012 and 2013 or does it imply that they will be doing the filming for 2 series next year?  Who knows ?  But, it is an interesting thing to think about.