Mark Neveldine first talked about their ideas for Crank 3. It's not 100% confirmed that they'll go 3D, but it sounds like if the technology advances by the time they start working on it, that's the way they'll go.
"We were actually thinking of trying to do RED 3D for Game for a while. We think it's the way things are going. The problem for us is that the rigs are still a little too cumbersome. They're a bit too big. So for 3D you tend to have a lot of locked off shots, things on cranes, things that are very controlled. We just don't shoot that way man, we like to just pick up the camera and run and go berserk and it doesn't really lend itself to 3D right now