Please let it be Black & White 3
A former employee for Lionhead, Franck Laurin, has a job on his Linkedin profile listed as "Senior animator- Fable Legends and Un-announced project. at Lionhead Studios". Lionhead is the studio behind games like Fable and Black & White, and it was founded by Peter Molyneux.
Lionhead has only released games in the Fable series since 2008, so it would be really awesome for them to create a new game, or to revisit Black & White. I'm sure this will turn out to be something related to Fable, but I can dream of playing Black & White 3 if I want to.