We'll see. I'm definitely hoping that with OpenCL we'll see a lot of physics implementations that are open to all parties, which is the direction AMD is heading with its latest Havok stuff. Both Evergreen and Fermi can run openCL, so I can't imagine why a developer would stick with PhysX for physics in any new games unless NVIDIA is paying money. Which they probably are.
Havok is Intel territory and AMD has scarpped all plans for using Havok.
They are now trying again with Bullet.
And developers use PhysX not soley because of the GPU acceleration possible, but also because it's a pretty good API with solid tools.