While Fable IV is a no-brainer for the team, Molyneux and co. have been tinkering a lot with Kinect during their Milo & Kate 'tech demo'. Something for E3?
It was during an interview that Molyneux - creator of classic franchises like Populous, Theme Park, Dungeon Keeper and Black & White - revealed he and Lionhead have something cooking at the studio. It's possible a tease or even a debut could highlight E3.
Perhaps he's dusted off a past glory like Black & White to go with Kinect?