I think most people here are missing the point, When he states that PC's can only utilize 2 GB of RAM he is in a way correct, they have to program the game to the lowest common denominator, the don't make individual PC specs per game, and so they make the code run on the lowest possible spec of machine, i.e. Win XP 32 bit for the vast majority of games, even those that demand Win 7 still limit the machine to 32 bit.
They have to do this to ensure the maximum market potential, they cannot remove 50% of the market place, couple this with the fact that nearly all PC games are developed cross platform with the PS3 and the Xbox 360 which are 32 bit, it means that the full scope of a 54 bit CPU/system is never utilized.
Now though they have 64 bit processors in the PS4, all games will be developed in 64 bit (well the majority) this should see major boosts in games, the AI for example should be a lot more sophisticated, Physics etc. The graphical boost will depend on the GPU selected for the machine, it will be a large jump from the PS3/Xbox 360 though.
The jump from PS1 to PS2 was huge, as was the jump from PS2 to PS3, I expect the same will happen here also. Sadly though development for 64 bit is more complex, and so I expect development time on games to grow and subsequently the cost of the games which are already exorbitant
but when these machines are released I do expect to see the games on the PS4 and Xbox 720 to be of a higher quality than the current stock of PC games, the PC will of course catch up and overtake the consoles due to the nature of PC's and their continued development, initially though these consoles will be great, especially at the 1080P display they are being aimed at.
What will hurt both consoles the most is not being able to play your existing collection of games, imagine a PC coming out and it was not compatible with your steam collection, no gamer would buy it, I have about 80 games on Steam no way would I just bin those for a new bit of hardware, I also have about 40 games on the PSN Plus network, not going to lose those either and I don't want two consoles in my front room. Hence I won't buy the PS4