We'll soon find out just how good an actor he really is. If he can deliver a performance that makes you forget his Sherlock Holmes character, then he's a real actor, and not a on-trick-pony.
One actor that comes to mind who was good enough to avoid stereotypes during his entire career is Christopher Plummer. He's remembered as Captain Von Trapp in "The Sound of Music", the evil priest in "Dragnet", and (surprise!) General Chang in "Star Trek VI: The Undiscovered Country."
Another thing in common between Cumberbatch and Plummer: they're both theatre actors. And many filmmakers prefer to work with theatre actors because, along with their prior acting experience, theatre actors know how to deliver a powerful performance in front of a camera just like they've done in front of a live audience.