What exactly is unique about PS4 that Cerny needed to design though? The Onion bus I guess? I think 8 ACE is a part of GCN 2.0. Maybe he was more involved on the graphics driver level.
Looking back on it now it all seems so obvious. And the biggest factor in the overall decision making for system architecture was probably unified memory which devs overwhelmingly gave them the answer to. APU for HSA, yields, and other benefits? Check. Bump up the ratio of GPU to CPU power? Check. Keep it under 150w? Check. Please use the latest GCN improvements. Check. Need high bandwidth? Interface the APU with GDDR5. Check. Oh we have 4gbit GDDR5 chips available now? Bump it to 8GB. Check.