I will consider only Rendering in my answer, and not touch Simulation, Animation, Modeling, etc. That's up to someone with a PhD or experience in those areas. read more
It can get better with a better approximations to Rendering equation (including better models for BSDF's (BRDF, BTDF) and BSSRDF, better integral approximations, etc.) which means more computational power. read more
technology has advanced and is better. hardware in ps3 and 360 are outdated and if they want to keep up at all with PC game developers they need to keep their hardware updated. this new gen should really just be looked at as getting a newer ps3/360. new OS, new hardware, to run the same type of games. graphics will be slightly better, games will be a bit larger. read more
Its fairly simple to understand why PC always has better graphics than most or any console game released on both the platforms. A PC does not come with the restrictions that a console comes with a PC fundamentally has no limitations on the hardware at all you can get a better GPU for PC than what is their in a console. read more