I wonder what will stop Keyshot from porting their render engine from CPU to GPU in the future. I don’t know a lot about how this works on a technological level, but at least Cycles from Blender has both and you can switch between them: a fully featured CPU mode with all the shaders and caustics and what not and a slightly less feature rich but blazing fast GPU mode.
I think actually Keyshot HAS to come up with something like this or at some point in time there will be a competitor who will offer the same Keyshot does, only on the GPU and much faster. And then Luxion would be in trouble.