Rogue One: A Star Wars Story will be released in theaters on December 16.
Clearly being a droid in the Empire has a huge downside, but this tidbit of information could hold a clue as to how C2-B5 will be used in Rogue One.
Beyond those two, however, Rogue One will mostly feature humans and different aliens continuing the battle against the oppressive Empire shortly before the Original Trilogy kicked off.
The Empire relies on these droids to maintain their machinery, but unlike the Rebellion, they don’t want them to be independent.