Sorry folks, look like the rumour is false.
[New York Daily News](http://www.nydailynews.com/entertainment/tv-movies/benedict-cumberbatch-cast-star-wars-episode-vii-rep-article-1.1444585):
> The British actor is not reteaming with his “Star Trek Into Darkness” director on J.J. Abrams’ foray into the “Star Wars” universe, Cumberbatch’s rep confirmed to the News.
> “There is no truth to the rumour Benedict has been cast in Star Wars,” a spokesperson for the 37-year-old actor told the News. “I think the rumours are circling because JJ and Benedict have just recently had a wonderful time working together on Star Trek .”
So that’s that. But then again JJ Abrams didn’t confirm that Cumberbatch was Khan until like 2 weeks after _Star Trek Into Darkness_ was in theatres, so at this point anything is still possible.