I agree with Xarx, the important thing is we get a true generational leap in processing power on at least two consoles in next gen so that multiplatforms can achieve a full generational leap in graphics.
I would be disappointed if Xbox 720 and PS4 were less than 10 times more powerful than a X360. I want them both to be 16 times as powerful than a X360. If that comes true then it's not a big deal for me if either of them is 20-30% powerful as the other.
And yes, it's extremely important we get the X720 and PS4 to be 10-16 times more powerful than a X360 or else the Wii U will be the lowest common denominator for all nexgen multiplatforms. From what we know the Wii U is at best 3 times faster than a X360, and if multiplatform games from 2014 and beyond were designed with those specs in mind it would feel like we were stuck in current gen (analugous to how a powerful gaming PC with two Nvidia 580 GPUs runs BF3 in 2560x1600 res and 8 AA in +60 fps but it still looks like a current gen game because the basic structure of BF3 is designed around the X360).







