'Sherlock' season 4 air date, spoilers: 'Sherlock' ends with season 4?

The highly anticipated fourth season of BBC's popular detective TV show "Sherlock" will arrive just in time for the new year. After years of hiatus, fans are excited to know what the eccentric detective Sherlock Holmes (Benedict Cumberbatch) and his trusted colleague Dr. John Watson (Martin Freeman) have been up to all these years. In addition, fans are worried that the next season could possibly be the last season for the British TV show.

Though nothing has been confirmed by the network or by the show's creators, reports are acknowledging the possibility of season 4 as the final season. British TV series aren't as lengthy as American shows. Hence, BBC could wrap it up in season 4.

Furthermore, reports say that another factor that suggests the show's end is Cumberbatch's availability. The lead actor reportedly has a number of projects lined up for him. The actor is now part of the Marvel Cinematic Universe for his portrayal of "Doctor Strange." Cumberbatch is expected to appear in forthcoming Marvel films; hence, chances are slim for a "Sherlock" season 5.

On a more optimistic note, there are reports claiming that Cumberbatch will return in "Sherlock" season 5, but the show will once again enter into a seemingly never-ending hiatus. In a previous interview with GQ, Cumberbatch told the publication that the "Sherlock" team will go into an indefinite hiatus before they start production for season 5.

"I'd love to revisit it, I'd love to keep revisiting it, I stand by that, but in the immediate future we all have things that we want to crack on with and we've made something very complete as it is, so I think we'll just wait and see. The idea of never playing him again is really galling," said Cumberbatch.

Watch out for more updates on BBC's "Sherlock" season 4.