In a recent interview, one of Sherlock's executive producers suggested that Moriarty (Andrew Scott) could be a big part of season 4.
Sherlock recently concluded its third season, which ended with the surprise twist of Moriarty's return. The revelation was something Steven Moffat and his fellow producers have been planning for a while.
"I can't really say what we're doing with that, but there is no last-minute whim in this," Moffat told Vulture recently. "We've had what we're going to do with Moriarty in place from before the second season. Exactly what we're going to do. I remember talking it through with Andrew Scott, who plays Moriarty. Wait and see what's going to happen."
The final episode of season 3 also featured Sherlock (Benedict Cumberbatch) shooting the evil Magnussen (Lars Mikkelsen). When asked if this would affect Sherlock into season 4, Moffat implied that there would be little to no effect.
"People are worried so much about that! Have we forgotten that John shot someone in the back in episode one? And then had a giggle about it? Do you know what? I would have shot Magnussen," Moffat said, laughing.
Despite the excitement of the season 3 finale, fans will likely have to wait a long time for season 4. Enstars previously reported on Moffat's comments about the fourth season, saying that it might not happen for two years.
"You know, we'll do what we can, but with no sacrifice in quality - that's the thing. If people have to wait two years, they'll have to wait two years," he admitted. "When's the next James Bond film? You know, it's not that kind of show that turns up all the time. It's just not. But the good news is, that probably means it will turn up sporadically for a very, very long while."
Sherlock seasons 1 and 2 are currently on Netflix while season 3 will be available on DVD as of Friday.