I like the idea of Jones becoming Moriarty’s anti-Watson of sorts. I think this ending would’ve definitely provided one last heartwarming twist the book was so lacking.

To be honest, this opening is a bit vague. I don't really know who is Deveaux or Jones and beside the author note where you said that you want to do a Moriarty sequel, I don't who is your narrator. I think that you're write very well, it was full of action and psychology but it would need a couple paragraphs more to put us in context. Is it Moriarty speaking? Why is he involved with the Pinkerton? Has he disappear in America? With just a bit more context, this story could thrilling