As development costs and piracy rates increase, the PC is not the bleeding edge gaming platform it once was. It is a second-class citizen in a world where high definition console gaming delivers the kind of shader-porn that was once only found on the PC. The problem is that while PC games still sell, they sell to a much wider market than those who crave the latest hardware, which ends up feeding back on itself.
No matter how freaking amazing your technology is, it is not a market to try and break into. This holds doubly true if your hardware needs a custom API. However, start-up Caustic Graphics is ignoring this and pushing ahead with expansion cards designed to make real-time ray tracing a reality.