I highly doubt that there will be a PS4 due to the fact that there is not a major graphics processor that is affordable to the public besides blu-ray. Sony is already making 3D games( Killzone 3), making the ps3 up-to-date with the graphics. With both the 360 and the PS3 the can update the system via software updates, but as far as a tech being invented other than 3D(which isn't new) they will just make a newer version of the system. A Wii 2 c'mon i wouldn't buy a Wii 2 for the simple reason it will fall just like the 1st one did, it will be awesome at first then crash later on cause the majority of gamers don't wan to leave the couch or bed to play games.
I'm sure that there will be a PS4 (maybe not with that name), a Xbox 720 (also not with that name probably), and a Wii 2 (Definately not with that name). It's more of a question of "when" than a question of "if". Eventually the games will reach their pinnacle on the current gen systems, and the companies will have to come out with a new system.
And I also don't see any one of these 3 companies dying out before the release of another generation of gaming systems, so, yeah, there will be another generation of these 3 companies at some point in within this decade
I read on the Playstation website, that they are in the process of making a ps4, but it will not be completed anytime soon. I'm not sure about the Nitendo and Microsoft new systems.
