Disney has confirmed that Lucasfilm will be at the D23 Expo this year in an email we just received:
It appears that SDCC has a deal that conflicts politically with Disney and they will not have a large presence there. While it is not exactly breaking news that Lucasfilm will be at D23, a confirmation is always nice. At the last D23 the Lucasfilm appearance was promised and then significantly pulled back for various reasons probably pertaining to the initial delay of the film.
D23 will be the event most likely to give us another look at Star Wars: The Force Awakens, Star Wars: Rogue One and beyond! We can’t wait!