I am reconsidering my thinking that Sony would launch in 2011 if Microsoft launched in 2010 (which I believe they are likely to do). Additionally, it might also be possible that the PS4's architecture would be UMA if XDR2 can provide adequate bandwidth for the GPU. With that in mind:
2010 Playstation 4
UMA 2 GB XDR2 8x2Gb devices @ 38.4 GB/s ea. (total ~300GB/s bandwidth)
40nm 4.5Ghz Cell (4 PPEs & 28 SPEs)
40nm 1.2 Ghz Nvidia GPU w/64 MB EDRAM
Does this seem more in accordance with reality? I think it makes a lot more sense than a NUMA design with 3 GB.
PS3 is already UMA-ish and was to be fully until the final cost of XDR hit them, I haven't seen anything from XDR2 that would suggest it'll be any cheaper. My guess is they'll pursue an option that lets the Tiawanese gov subsidize they're memory needs like everyone else.
Why would they go with a 40nm Cell when they're already at 45nm? That makes no sense at all. 4 PPE's are unneccessary, 2 PPE's would be more likely with possibly a 3rd if they went with a unified architecure approach. 28 SPE's is again unneccessary unless they went with a unified architecure, 12 is more likely for a stand alone Cell CPU.
At this point, I doubt we'll ever see another Nividia gpu in a Playstation. It's not that everything is Nividia's fault, Sony made it's fair share of poor decisions too, but in the end (and that's what counts) they charged Sony a huge premium to repackage a 7800 with UMA which wasn't even used (fully) all the while using that money to finance their next gen chip which Sony couldn't even use (original G80 was as big as Cell and RSX combined with a 512 bit bus). Add to it, they launch the G80 3 days before the RSX launch which made it effectively obsolete on launch and you have Sony going wtf. To put it another way, Sony paid NV big bucks to create magic and instead got card tricks in return.
As to edram, it's basically there to stabilize your bit rate to the gpu in a uma design. Yes you can do some tricks to take advantage of the larger bandwith but ultimately you can't pass thru more than your fed. It may have made sense in 2005 for Xenos but I don't believe it does today or in the future.
Looking at whatever future Playstation Sony puts out, you should first look at the failings of the last one. In this regards, the biggest failing with the PS3 was Sony putting themselves in a position where they had to make major compromises in the grand design scheme just to get the product out the door. That was so un-Sony which I'm sure it won't happen again and will probably lead to a much more conservative approach to their next one which would also be in many respects un-Sony.
But I think that CPU will still be there. The balance in computational resources between CPU and GPU will be decided with efficience in mind in regard to various workloads.
