Yes, there is a Sly Cooper movie on the way, apparently. It's coming out in 2016*. And it will feature the return of Sly's nemesis, Clockwerk.
The movie will be penned and directed by Kevin Munroe, the guy behind 2007's TMNT, with the animation being handled by Rainmaker and Blockade Entertainment, who are also currently working on a similar Ratchet & Clank-related project. The movie's Facebook page has a few words to say about the movie's plot: