Rumor has it it'll be a 6770
I am afraid the current rumors are worse.
For Xbox "720" / Durango, it's rumored to have HD6670.
http://www.ign.com/articles/2012/01/24/xbox-720-will-be-six-times-as-powerful-as-current-gen
I am not sure I believe this rumor though. It sounds way too weak.
On the PS4 side, things aren't looking better though.
AMD's A8-3850 APU and HD 7670 GPU.
http://www.ign.com/articles/2012/04/04/sources-detail-the-playstation-4s-processing-specs
HD7670 is a re-badged HD6670. The combined power of HD6670 + A8-3850 (HD6550 GPU) in CrossFire is <= HD6770 (but that's assuming perfect scaling).
Based on these specs, next generation tessellation is going to be severely limited since HD6670 has awful tessellation unit. By end of 2013/early 2014, this type of GPU power will be slower than AMD's APU at the time and by desktop PC standards completely budget level. Remember that HD6770 itself is just a re-badged HD5770.
In my eyes, anything less than HD6950/GTX560Ti or even HD7850 is a complete disappointment for next generation consoles because I have a feeling they'll also stick around for 7-8 years. Selling a console in 2013/2014 with HD6670 GPU after nearly eight years of Xbox360/PS3 would be a major slap in the face. However, given that MS wants Xbox to be a media device first and foremost, I can easily imagine them spending $50-60 integrating Kinect and cost cutting on the GPU.
I would love to see
HD7950M from laptops to make it into PS4/Xbox next.
- ZeroCore power for amazing idle power consumption
- Just 50W of load power
- 2GB of VRAM
- Good tessellation performance on the AMD side
Sony is bleeding $. They can't afford to sell hardware at a loss as was the case for PS3. For that reason I am ruling out a fast GPU in their console.
For MS, they seem to care more about capturing more market share from social/casual gaming, focusing even more on Kinect and extending media functionality to get people to want an Xbox for things other than games. Given MS's lack of exclusive games, I am not seeing any evidence that MS cares about capturing even more hardcore gamers especially since Kinect has been a success for them. I think MS realizes the real growth is capturing some of Nintendo's fans instead and other casual gamers. The fraction of hardcore gamers who will leave PS3 for MS's console is probably not large enough, but there are tons and tons of casual gamers that might consider getting Xbox and playing arcade games, Minecraft style games.
Maybe if these consoles are very underpowered, developers will start making cutting edge games on the PC again and porting them back to consoles (especially since PS4 will have AMD CPU).
Here is another article on Unreal 4 engine and how it will simplify coding for developers. It has real time dynamic lighting model:
Unreal Engine 4.0 - The Imagination Engine: Why Next-Gen Video Games Will Rock Your World (WIRED Magazine)