It is almost inevitable that fans of "Sherlock" have another long wait in store for them. There is much speculation that "Sherlock" might not return before 2016, and BBC has yet to officially confirm that "Sherlock" is returning for Season 4.
Steven Moffat and Mark Gattis, however, have confirmed that fans will get to see two more seasons of "Sherlock." Moffat had said that they have plotted out the entire Season 4 and Season 5.
In "Sherlock" Season 3 finale, the dead Prof Moriarty suddenly came to life on T.V screens all across the country, saying "did you miss me." In the Season 2 finale, he had committed suicide by pulling the trigger of a gun in his mouth. According to Moffat, bringing back Moriarty was not a last minute plan.
Moffat has not revealed how he intends to use Moriarty in the new season, but he said to Vulture, "... but there is no last-minute whim in this. 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." He added that Sherlock must have a Moriarty.
In an interview with TV Guide, Moffat had said that they are going to "account for" everything that they have shown in Season 3 finale of "Sherlock" and nothing will be left "dangling."
Moffat also talked about Molly and said that her character has developed "hugely." According to the co-writer, Molly was not supposed to return after her first appearance, but "she worked so well. Louise Brealey was so good."
In another interview, as reported by Enstars, Moffat indicated that Molly will continue being part of Sherlock, as "every time we bring a woman into Sherlock, it works hugely well."
Moffat had said they have a set of best ideas for the new seasons of "Sherlock." He and Gattis had a "whole set of specific story ideas mostly for Series 4 but reaching into Series 5."