What happens if those expectations aren't right? What if next-gen hardware is something completely different, like ARM and GPGPU, because it gives way better bang-per-buck? What if the programming environment takes a shift to support different paradigms (GPGPU)? What if the hardware choice wants a bleeding-edge tech like stacking for better economies, necessitating a wait until 2013?
Then, as I stated, it would be rather difficult to conform to such a timeframe given what we know at this point WRT developer involvement.
The decision isn't made in a vacuum.
There are pros and cons.
Launching in 2012 with derivative hardware (not necessarily "weak" mind you) has the advantages of potentially
capturing first-mover/hardcore gamers (they like to buy the latest and greatest and spend money...it would take something special to convince them to buy another machine which does roughly the same thing within a year),
mindshare for others that would like to purchase, but may not be able to afford it, being the
dev base for nextgen development (MS seems to already be filling this void by establishing early NG dev kits at EA, Ubi, Crytek, Epic),
games library (getting started earlier means more games which have this hardware in mind will begin, and end on said hardware) and the "
friend effect".
Cons are: more expensive to launch than 2013 (assuming roughly equal hardware spec budget), potential disruption of existing xb360 base (not likely, given the target demographics at a given timeframe), potentially being outclassed by competitors hardware, thus losing the hardcore/first-mover base (which is why it would be stupid of them to come to the table with a "happy meal" for hungry gamers which could lead to a breakdown of all of the advantages listed above).
Choosing which hardware to put in is less important than choosing what the BOM budget for said hardware is IMO.
Simplified and unrealistic example of what to expect but:
In other words, lets assume the "GPU+CPU(+Ram)" die area for xb360 and ps3 was 500mm^2.
One chose to literally scale the exact same chipset, features, and functionality of their existing hardware box and produce it on 28nm with the same size 500mm^2 (literally a ps3 x8) and the other chose 250mm^2 but using whatever latest and greatest architecture.
I'd go out on a limb and say the 500mm^2 "ps24" with 4gb ram, 64SPE, 8PPE, 4mb cache, and RSX (x8) launched in 2012 would wipe the floor with 250mm^2 "Xbox Super Arm GCN edition" with stacked memory and a total of 2gb ram in 2013.
One of these will have toolsets that let developers shine with what they already have cooking and will support every game in their DLC library and even cross-generational online multiplayer. The other, won't be on the shelf for a year, will ask customers to buy all their DLC again (this time, with tesselation!), and will have mixed reviews when it comes to the visuals of the more limited library which is available.
Extreme example but it makes my point that Die Size budget is what will make or break these machines in providing an edge.
Back to reality:
By "derivative", I was speaking more from the standpoint of the
CPU architectures (Sorry if that wasn't clear by now). Not that they will be
exactly the same as they are now but scaled up. I expect there will be some changes, but nothing radical and nothing that would break BC.
As for GPGPU, I don't see a reason why either machine couldn't have GCN while still having BC. GCN will be available commercially in q1/2012. Way back in 2004, MS had ATI put together a chip which utilized tech ATI wouldn't have at retail for 2 more years. GCN should also not have a significant problem in replicating or emulating Xenos or RSX.
So I'm not seeing a reason for GCN to not be in a 2012 console. It will be readily available, flexible, affordable, and compatible.
As for Ram, it's not as though there aren't options ~today that would provide the bandwidth necessary for a nextgen console. GDDR5, XDR2, EDRAM+DDR3 (ala xb360).
_____________________________________
Making the move in 2012 would not preclude some special sauce technology (that I'm aware of) that will be commercially viable in 2013 that isn't available for 2012.
If there is and it would provide a sizable jump in either equal performance for half cost (
lifetime not just teething problems at launch) or double performance for same cost, I'm all ears/eyes.
It would have to be significant (perhaps not as extreme as illustrated above) to offset the loss of a year on the market (and all that entails), and potential loss of BC.