If the fourth season of Sherlock is really remembered as its last, blame scheduling.

Since “The Final Problem” premiered almost six months ago, the show’s immediate future has been the topic of heated debate online, as viewers deliberate over what’s next for Benedict Cumberbatch’s eponymous sleuth beyond 2017. A fifth season has been floated numerous times in the past, but it’s “at least two years away,” according to series stalwart Andrew Scott (Moriarty).

That’s largely because of Cumberbatch’s (and indeed Martin Freeman’s) stacked slate, but there’s also the very real concern that series showrunners Steven Moffat and Mark Gatiss will become too tied up with other TV projects. Case in point: Dracula, a new take on Bram Stoker’s horror classic that has already set up shop at BBC America. All of this has led many to believe that Sherlock has been placed on an indefinite hiatus,...