So, that should have been 2016?
What has been done on the CPU has worked quite well. It has changed gameplay mechanics, and added immersion. That has not been done with GPU physics. GPU physics has been used only as added eye candy, thus far.
It's nothing to do with PhysX or not. If AMD had one that only worked really well on their GPUs, the same problem would arise: to make it really work, it needs to be on the CPU (like the very few good uses of PhysX on PCs, and all uses of it on consoles), or you would need to limit your game to only running for owners of one or the other major AIB GPU vendor. Then, you would need to tackle the problem of batching enough physics work per frame, and keeping enough CPU work to do while waiting for the results (a problem solved by just doing it on the CPU).
In our PCs, and the last gen of consoles, the GPU has been at a huge disadvantage, being tens of thousands of cycles away from the CPU, often more on PCs, going through all the software layers. The PS4 won't have the latency problem to the GPU, and near-future PC CPUs won't suffer from lack of computational power. Our PCs will still be better served by doing it on the CPU, for the same reason as they have up until now: the GPU is a cross-country trip, while the SIMD registers are right there. AVX2 is right around the corner, and will close that computational performance gap.
