"We were serious about it. We went to all the big studios in Hollywood and pitched the idea," Tameem Antoniades told Destructoid. Unfortunately, Hollywood wasn't interested in Ninja Theory's vision: to create a feature-length film using real-time graphics powered by Unreal Engine 3 (used for the game). "They don't want to do it for cheap. They want Pixar and the other higher end [studios] to do it for 100 million dollars or 60 million dollars. To do it any other way is considered a huge risk, so it just didn't wash."
We can certainly understand the studios' hesitance towards the concept. While Enslaved certainly looks good, an Unreal-rendered movie probably wouldn't be pretty enough to appeal to the mass-market movie watcher used to Pixar. And with Enslaved having yet to prove itself as a valuable IP, it's no surprise that the film adaptation never came to fruition.