The reveals continue today as EW has debuted a handful of new images and confirmed the amazing news that James Earl Jones will return to voice Vader. Look, anybody can do Vader's voice but there's always something special when Jones does it himself, as he does when the character shows up on Star Wars Rebels. As for how big of a role the Dark Lord of the Sith will have, Lucasfilm's Kathleen Kennedy says it will be small but important...
“He will be in the movie sparingly. But at a key, strategic moment, he’s going to loom large.”
Gareth Edwards adds that Vader is something of a myth within the Rebellion and the Empire...
“Within the Rebellion, it’s not commonly spoken about. Within the Empire, there is the culture of knowing of the existence of Darth Vader. There’s definitely an underlying feeling that there is a power – a dark power – available to the Empire and that if you overstep your mark, you will suffer the consequences.”
It's a good sign that Edwards is a part of the publicity tour, also. It should help to calm fears he's been completely replaced as prior reports suggest.
As for Ben Mendelsohn's Director Orson Kennic? Let's just say he and Vader aren't pals. Kennic is resentful of Vader's power within the Empire and will do whatever it takes to gain the Emperor's favor.
Something tells me Vader will be there to make sure Kennic fails in whatever plan he's cooked up for the rebels. Rogue One: A Star Wars Story opens December 16th.