Reality is that it's still too early. Fast forward a few years and we'll be there.
This generation has really moved to more convenience, less quality, so I expect streaming to really take off and I'd expect this will be the last of the physical media, or at least physical media will become a niche market, like vinyl is now. Bluray is still vastly more content than a streamed movie. Bitrate still has a part to play over straight resolution.
Bluray bought along uncompressed audio, so unless this is being substantially improved, most existing receivers should be able to play the audio delivered over hdmi? Simply means one hdmi to the display device for video, and another, or ARC on from the TV to the receiver for audio.
PS4 is quite old now, released around Dec 2013. I'm surprised the price has stayed as static and high as it has really. Maybe the upcoming PS4.5 will be a bit more capable, but essentially it's old tech and pre this 4k bluray arena.