Actor Benedict Cumberbatch smiles as he arrives at the 2014 Vanity Fair Oscars Party in West Hollywood, California March 3, 2014.
Actor Benedict Cumberbatch smiles as he arrives at the 2014 Vanity Fair Oscars Party in West Hollywood, California March 3, 2014. REUTERS/Danny Moloshok

The online media is abuzz with speculations that "Sherlock" Season 4 is likely to premiere in 2017, as Benedict Cumberbatch, who plays Sherlock Holmes, has signed on to star in Marvel's "Doctor Strange." The actor is going to portray the titular role of Stephen Strange in the movie, which is slated for release on July 08, 2016. The shooting of this movie is said to begin in 2015. This means that Cumberbatch's busy acting schedule may once again push ahead the production schedule of "Sherlock" Season 4. BBC and producers have not yet confirmed the date of production of three episodes or the premiere date, but it was expected that the new season will premiere in Jan. 2016.

As previously reported, it is the busy acting schedules of Cumberbatch and Martin Freeman, who plays Dr Watson in the show, that have delayed the production of "Sherlock" Season 4. Unconfirmed reports suggested that according to the original plan, the filming of the new season was expected to begin in autumn this year.

Meanwhile, the filming of a one-off episode is scheduled to take place in Jan. 2015. This episode is said to be the 2015 Christmas special episode. According to reports, the filming of Season 4 was expected to follow later in 2015.

Mark Gatiss and Stephen Moffat, co-creators of "Sherlock," have indicated that Season 4 is going to be more devastating and darker than the previous three seasons. In a statement, Gatiss said that the new season is set to take Sherlock Holmes and his buddy Dr Watson "into deeper and darker water."

Recently, Gatiss said that Season 4 should match Season 3. Radio Times quoted him as saying, "What we want to do for a fourth series is match [series three] ... but it's not a question of saying 'Well we need a baddie on that scale [of Charles Augustus Magnussen].'" He added that it is about "trying to find stories that have that kind of scale to them."

Earlier this month, DVD and Blu-ray set containing all three seasons of Sherlock was released.