Is everybody familiar with the phrase "epileptic trees," meaning crazy fan theories? 

One such theory, regarding canon, was that Holmes did in fact kill the blackmailer, Milverton, and writing another shooter into the story was just cover-up by Watson.

Sherlock's actually shooting CAM in this series might suggest that Mofftis are paying attention to those wild guesses.

But another theory is that the Holmes who came back from Hiatus was an impostor...so the implications are scary, although it would at least redeem the "real" Sherlock.

But the events of TSoT we want the real Sherlock to have done.