Navi was a thing before even PS4, why people keep spouting BS I do not know. All Cerny does, as anyone would do in any comparable position was work with AMD to fit their needs.
This. People have taken "co-develop navi" out of context.
They have co develeped their own custom chip based on Navi.
As for power... I really expected Ms to have it in the bag based on how development of X was handled. Now I'm not so sure!