1. It Happened In The Books
This is an obvious choice for the number one spot. The death of Professor Moriarty and subsequent disappearance of Sherlock Holmes took place in the Final Problem, a story published in December 1893. If the legacy of Arthur Conan Doyle's creation can remain undiminished over a century after this story was written, then there is nothing to be concerned about. Infact the popularity of the series increased, as Doyle was forced by popular to demand to resurrect his lead character from Reichenbach.The modernised version of Sherlock has made it abundantly clear that Sherlock survived his fall, so there is even less reason than there was in 1893 for the series to decline.