I think games like Killzone 2 and God of War 3 will have an effect on 3rd parties, if they release games running badly on the PS3 they will start to look horribly incompetent and lazy in many people's eyes.
I am looking forward to what the Crytek guys can come up with on the PS3, I think they are too ambitious on the technical front to not try to rival other games on the PS3.