Well, after one failed attempt after another, Hollywood seems to be giving up on most of their attempts to replicate the Marvel Cinematic Universe. Star Wars has been slowed. "Universal Monsters" seem to have been held at bay. And the few that remain, like the Godzilla/King Kong or Shyamalan franchises are quietly and hopefully moving along one film at a time.
If the cinematic universe business had been more successful, would we have seen the movie business eventually getting to Conan Doyle?
Sherlock Holmes would start the Conan Doyle Cinematic Universe, of course. Irene Adler, Professor Moriarty, Mycroft Holmes . . . all the usual suspects . . . would be quickly considered for films, of course. But after that?
Well, Professor Challenger has to get a movie. He's met Sherlock Holmes in fiction before, though that meeting was not from Doyle's pen.
Brigadier Gerard would be another option, though he lived and died long before Sherlock and company, though a distant prequel would be interesting. Gerard could even run into one of those cursed Baskerville kids or do something else to set up a later film in the series.
Conan Doyle's historical characters really are the hardest challenge for a Conan Doyle Cinematic Universe. Sir Nigel and the White Company, both existing in the 1300s, might fit with each other, but getting that connection to the Victorian era five hundred years later is practically going to take some time machine borrowing from H.G. Wells.
Throw in the pirate Captain Sharky and one starts to see that the Conan Doyle Cinematic Universe has to play across time to get its full use of the author's characters. But pirates, knights, detectives, dinosaurs, and a little comedy as well? There's a lot of fun to be had if someone could have worked it all out.
But, alas, the cinematic universe trend seems to have moved on before working its way to ACD. The thought of what could have been still intrigues, though.