Kyliestrutt's thread on the PS5 here : http://gamrconnect.vgchartz.com/thread.php?id=203238&page=1 got me thinking about how 2013 was kind of a rough time in many ways to launch gen8.
I think in many respects, very similar systems to PS4/X1 could have been achieved in 2011-2012. Maybe to hit the price 4GB would have been used, but the overall result (both somewhat struggling at 1080/60 unless notable corners cut visually, many 900p and even 720p titles) would have been similar.
On the flipside, what about Nov. 2015 for PS4/X1?
Zen 3Ghz Quad-Core with GPU around 2x-2.5x faster than HD7850?
With 28nm stalling us for so long, and Jaguar being somewhat terrible, I think both CPU and GPU elements could have been generationally superior if they had just waited 24 months. It's especially tough if you enjoy full-resolution non-scaled visuals, and 60fps gameplay. Both are seldom hit by PS4 or X1, either by the bottlenecks of a mid-tier GPU, or a netbook-level CPU with a ton of slowpoke cores.
There have been very few gen8 exclusives so far that couldn't have been done on PS360 with lowered resolution/assets. On balance I would have preferred plowing ahead with PS360 until we got past the Jaguar/sub-2tflops 28nm APUs.