In an interview with Variety, Moffat compared Sherlock with the TV series "Doctor Who", noting that most of the series have a certain "wear term". "As soon as Benedict Cumberbatch decides to leave Sherlock, what will we do? We will close the series, that's what we will do. " But the "Doctor Who" even with the departure of the next lead actor will continue its existence - because, according to Miffat, "any part" of this series can be replaced.
However, Cumberbatch himself is not going to abandon Sherlock Holmes - in early 2014, in an interview with USA Today, the actor promised that he would continue to act in the series while his character would "grow and develop." And at the end of the same 2014, in an interview with Vogue, Cumberbatch added that, if the high quality of the series remains, it does not present at all that someday gets tired of the role of Sherlock. "I would like to play it even an old man."
Victorian special issue "Sherlock" will be broadcast at the end of this year, and the 4th season of the series, according to preliminary information, will begin to show by the end of 2016.