i think many are missing one factor in the argument.. the key people who were behind the success of PS4 is no longer in charge. Kaz, Jack Tretton, Andrew House, Adam. Dont know who is designing the next console.. is it Mark Cerny, or someone else?.. it will be stupid of Sony not to hire him again for PS5.
The thing is sony has a history of getting cocky and over ambitious with success, like PS2 to PS3. so with new management I wont be surprised if we start hearing about the rumbling of PS5 announcement early 2019, with the release in fall.
And all the prominent developers have gotten Black box but those kits contain high end component which in no way will make onto PS5 unless it costed $1000. the only utter importance in the box are API's and framework