What makes me sad about the show is that there are questions (although admittedly not very big ones) that are never answered. She thinks the shaky snipers were actually kids - sort of as a "fuck you" to Sherlock. I didn't really get what she meant ô_O. Personally I always thought the snipers were played by crew on too much coffee, so I never felt the need for an in-story explanation.
My god, think of those snipers! It was probably their last job ever. Because "No one ever gets to me and no one ever will." makes me pretty convinced that the only one who gets to work with Jim directly is Sebastian Moran. So after the Pool Incident all the other snipers had to be disposed of, I imagine.