I believe Nintendo already confirmed that Wii U has an RV770 style GPU in it. Chances are that Microsoft is going to continue with AMD as well. That only leaves Sony as the "unknown". Since consoles have limited cooling space and the original Xbox360 was heavily criticized for being loud, I believe there will be an added emphasis on power efficiency/heat. In this case, both AMD 5000 and 6000 series chips are simply superior in terms of performance / Watt compared to GTX4xx/5xx series. Therefore, it's only makes logical sense that AMD is the preferred supplier for consoles in the next generation.
In addition, NV's
higher end chips need a more costly 320/384-bit memory bandwidth which will add significant costs to the console motherboard design. It would be far cheaper to implement a 256-bit memory interface with GDDR5, which again AMD provides.
Either way, it's far more important to see how powerful the GPUs will be, rather than what vendor will provide them. I mean if they put an HD6770 or an HD6550 as part of the APU into the PS4, I will
not be impressed, regardless of how efficient that chip is. So I am waiting until exact specs are released. At least if all 3 GPUs will be provided by AMD, there will be no more fanboy arguments over which GPU is faster since you would be able to compare them
across AMD architectures
It is unfortunate that the consoles are launching during the "stagnant GPU" time though. GPUs haven't really improved in performance that much since HD5870 was released in Sept of 2009. I am still hoping either Sony or Microsoft squeeze a 28nm Kepler or 28n HD7000 series into their 2012-2013 consoles, even if it is one of their mid-range offerings (given the limitations for power consumption). But that's probably unlikely considering development is way under way for both. I am guessing there is a 95% likelihood the next gen PS4/720 will have an HD5000 or HD6000 derivative GPU.