Charlie Demerjian's SemiAccurate posted an exclusive about the specifications of Sony's future PlayStation 5 console. The meat of the article is behind a paywall but a summary appeared on ResetERA.
The next-gen PlayStation will reportedly feature a custom-design, AMD Zen-based processor. The graphics part will not specifically be Navi, but it will use Navi as its base architecture.
A large number of development kits reportedly went out and a 2018 launch date (or reveal) of the PS5 can't be ruled out. It's not definite, but given the amount of dev kits, Demerjian is positive that a launch is getting close.
Furthermore, he also notes there will be VR features implemented at the silicon level.