I really think people are underestimating how much different this gen will be vs previous generation transitions. Before you had completely new architectures and engines running between generations. Maintaining completely different builds of the "same" game for each architecture.
PS5 will run the same OS as the PS4. Developers will have the ability to restrict their games to only run on PS5 (if say they're developing something that requires something that the new system offers), but it's not like Sony is starting over with the base architecture like PS2 to PS3 or PS3 to PS4. I really doubt we're going to have to wait years again for things like folders, custom themes, Spotify etc to be added into the OS. It'll be the same OS running across all PlayStations. I also don't think we're going to have to wait for all the streaming apps and services to be rebuilt for PS5 like we did from PS3 to PS4. The PS5 will just run the same apps as the PS4 does.
With this in mind, I see their pricing approach similar to Apple's approach with iPhones– want an iPhone but don't have a ton of cash? Get the previous generation iPhone 6/7/8. Want the latest and greatest hardware? Get the iPhone XS. Developers can choose to update their apps to take advantage of the new hardware features and power, but it's not like if you get an iPhone 7 you're running a different app than someone on an iPhone XS (unlike when someone was running the PS3 version of the same game that's available on the PS4). If the app/game is updated to take advantage to of the new hardware it's the same codebase as those running on older hardware. Apple doesn't really care which iPhone you buy- they care most about locking you into the ecosystem so in the future you upgrade to another iPhone (and continue to invest in the iOS ecosystem).
I'm not saying there won't be experiences that are exclusive to the PS5, but I am saying that the PS4 will be the entry level PlayStation and it'll be supported looooong into the future (unlike devs dropping support for the older architectures in previous generations).
The lines between generations will become very blurry. Especially when you have the same game running across the PS4, PS4 Pro, PS5 and PS5 Pro.
Thats it, but don't hope for understanding.
Most gamers seem to live in a bubble of the gaming past.
I also think that this could leave the possibility for a higher pricing of the new consoles if the old consoles are still supported down the road.