I didn't know Cage was in Snowden, that makes me a little more interested in the film but it'll only be a small role by the looks of it.
Nicolas Cage doesn't need a comeback. He's been an A-lister, he's won an Oscar, what more does he need to do? He can continue to do his own thing and continue to be a fantastic actor in everything he does.
(That being said, I'd love to see him in more interesting roles than his current action rubbish, and be in bigger films)