Sherlock: 6 Reasons It Needs To End (And 4 Reasons It Should Come Back)

3. John and Sherlock's Relationship Is Now In An Interesting Place

As much as we would like to see more from the supporting cast, however, an even stronger reason for why Sherlock needs to return is that The Final Problem moved Sherlock and John's friendship into a very interesting avenue that would be fascinating to see explored.

You might recall that John's wife Mary was killed at the beginning of the season, which caused a rift between the two friends. Come the end of the finale, though, we see that the Baker Street boys are now stronger pals than ever and are in fact bringing up John's baby daughter Rosie together.

The idea of Sherlock and John raising a child together while still solving crimes is such a hilarious and touching one that it needs to be explored in future episodes. Given the long gaps between seasons, the show could become like a crime drama version of Seven Up, as we would see Rosie grow up under the strange parenting skills of her two dads in intermittent intervals.