I think people are getting mixed up with what 4D actually is. It's not Dr Who, it doesn't mean timetravel as such...but movement over time...in essence, 4D means animation of 3D objects.
Prediction (June 12th 2017)
Permanent pricedrop for both PS4 Slim and PS4 Pro in October.
PS4 Slim $249 (October 2017)
PS4 Pro $349 (October 2017)