While fans await the return of the hit series "Sherlock" for its Season 4, the show's special slated for Jan. 1, 2016 is expected to appease viewers' anticipation. The trailer for the Victorian special was recently released, which provides several clues on the plot of the episode. Meanwhile, there are rumors that "Sherlock" Season 4 may be its last, given Cumberbatch's increasing popularity and more hectic schedule.

According to iDigitalTimes, co-creator Steven Moffat mentioned the possibility of "Sherlock" ending once lead actor Cumberbatch decides to leave the show. In an interview with Variety, Moffat said, "Once Benedict Cumberbatch gives up Sherlock, what are we going to do? We are going to stop, that's what we are going to do."

Moffat's statement was in relation to the show "Doctor Who." In explaining about the difference of "Doctor Who" with other shows, Moffat said that other TV series have a "built-in mortality" and are entirely dependent on its actors, just like Cumberbatch's "Sherlock." "Doctor Who," however, is reportedly indispensable and "will carry on forever, because you can replace every part of it," Moffat explained.

Due to Moffat's statements, others began speculating that Season 4 may be "Sherlock's" last since Cumberbatch is getting busier due to his increasing popularity. The actor recently played the dragon Smaug in "The Hobbit" trilogy, and he is currently filming for the Marvel movie "Doctor Strange." His "obligations to star in future Marvel films" may reportedly leave him with less time to do other projects like "Sherlock," says Christian Today.

Though that's the case and despite the very few details so far about Season 4 of "Sherlock," the show is expected to return in the latter part of 2016, after its Victorian special airs in January.

Speaking of the "Sherlock" special, "The Abominable Bride" trailer was recently released, and although the video is less than 30 seconds short, Screen Crush says it provides certain clues about the episode's plot. Since the special's story is not related to the latest events in "Sherlock," "The Abominable Bride" sees Sherlock and John Watson (Martin Freeman) meeting for the first time.

Watch the trailer below: