Sony aren't pushing UHD into our homes because the significant growth of adoption of streaming media, and streaming 4k services points towards those services dominating the future of entertainment distribution, not UHD blurays.
Yeah, this, and there's nothing to add (but still I'll add my opinion
).
Except in USA BRs are almost not selling at all, DVDs are still selling 10 times more (A LOT cheaper, enough for most people) and people are gettings used to streaming VOD/SVOD things), so... If Sony, the creators of BR discs don't support UHD BR so much, I think there's a message in it... Streaming/SVOD is winning. To me the only downpoint of VOD is the lack of multilanguage tracks. I'm French and when I want to buy/rent a VOD movie I don't do it because I've to chose to buy the French version or the version with subs, it's a big downpoint and they should fix that ASAP, exept that, streaming is the future and Sony knows it. They have their own VOD service (PS Vue, etc) so they promote it too...
We'll see when the PS5 comes out if the UHD BRs became a thing, and if it did, the PS5 will for sure have a UHD player.
This time Sony is pushing the Streaming, not a support (unlike the DVD and the BR), let's see what will happen. They also made the (smart IMO) choice of the PRICE, by removing the UHD player they save money (15$ per machine I heard, it's huge in terms of margin, multiplicate by the numbers of PS4s already sold for exemple, you'll see) and we can have the "high end" PS4 experience for 399$. The truth is it's CHEAP for what it is! A huge boost for just 50$ more is great (the 1TB PS4 Slim is 349$, PS4 Pro 1TB is 399$), even though there's no UHD player.