How will the Wii U fit games on the PS4, if the PS4 will have 7GB RAM available?

[Pemalite]

curl-6 said:

Not necessarily. For example, a Modern Warfare Wii dev confirmed the enemy counts weren't reduced.

To be fair, Modern Warfare is not that demanding of a game, it uses a modified Quake engine which could run on a Dreamcast console. (A console that came before the Playstaion 2.)
John carmack is amazing at making game engines run incredibly tight and at a high framerate, that's where most of the praise came from with that engine and that translated over to Call of Duty.
Battlefield 3 however had map sizes and player counts reduced to fit on the Xbox 360 and PS3's anemic hardware.