The PS4 driving sim is officially set for a fall 2017 release...for now.
One thing that hasn't changed, however, is the racing franchise's place as a graphical tour de force. On PS4 Pro, Sport will feature 4K, HDR, 60 fps, VR support, the works. Couple that with the improved audio and a solid-yet-accessible physics model and you have quite the technical achievement.
Gran Turismo Sport will be out on PS4 and PS4 Pro this fall....unless it gets delayed again. Which, with Polyphony's track record, isn't all that unlikely.
However, PS4 owners looking to get in on some racing right freakin' now can sign up here for the ongoing closed beta—The Drive's first impressions of which can be found here.