As "Sherlock" concluded season 4 after a three-episode run, the rumor about show's cancellation started doing the rounds. However, it looks like all the parties are interested in taking it forward to season 5.
According to the writers, Gatiss and Moffat, Sherlock Holmes, played by Benedict Cumberbatch, discovered compassion in his heart, that has been central to the detective's brilliance in solving crimes. Hence, should there be a season 5, the writers believe that it will take the viewers to the starting point.
Gatiss revealed to Radio Times in an interview that their original plan for the series was to go into a backstory and show these characters as younger men, showing what makes them the men the viewers know them to be. Gatiss also explains the Rathbone Place reference at the end of season 4. This is the allusion to Basil Rathbone who played Sherlock Holmes in the 1940s, inspiring the writers and showrunners to adapt the show into modern-day series, hinting that adventure of Sherlock and Dr. Watson will always continue.
Furthermore, Moffat also explained in the interview that Sherlock is now aware of his emotional intellect and how he is smarter than Mycroft. It is not because of his actual smartness but because of the touching connections that he made with other human beings, gaining important wisdom along the way. Moffat also added that Sherlock may not be as clever as his sister Eurus or his brother Mycroft, but he will always have a winning edge against them because he is emotionally smarter, stronger and better.
Meanwhile, there is also speculation that "Sherlock" season 4 may well be the last one. Moffat, when asked about the future of the BBC show, said that "If this is the last time - and I'm not planning on it to be, but it might be - it is possible that we could end it," The Independent reported.