As to Jimmy Sony saying they'll continue to support the PS4 for 3-4 years, this is standard business for a high selling console.
Sony in an investor meeting a while back said the PS4 will remain the engine of profitability and engagement or something like that. Basically its the super profitable console. Costs are low, tons of users, lots of software sales.
It does not mean PS5 will only get cross gen games. Here's how I think Sony's games are/will be:
PS4/PS5
Spider-Miles (predictable)
Horizon 2 (sucks ass)
Sackboy (predictable)
The Last of Us 2 multiplayer (predictable)
MLB The Show 21/22... (predictable)
50/50 chance of cross gen - Gran Turismo 7 (idk yet)
PS5
God of War Ragnarok
Demon's Souls
Ratchet & Clank Rift Apart
Destruction Allstars
Spider-Man 2 (likely fall 2022)
new Uncharted game (if real)
Sony Bend's next game (Days gone 2?)
Guerrilla's other game (SOCOM?)
Naughty Dog's next game
etc
Plenty of next gen exclusives.
I bet Sony's original plan was to have Horizon 2 out this year as a PS4 game. Lots of Guerrilla devs worked on Death Stranding, which could have delayed HFW. I suspect they wanted TLOU2 out in February, Ghost in May, and Horizon to be out by September or so. Clearly its a bit behind and got pushed onto cross gen. The PS3 got GT6 after PS4, and PS2 got GoW2 after PS3. Delays happen & cause overlap.
It kills my next gen hype for the game. But now I just add it to the list of great PS4 games, right alongside Ghost and TLOU2, and many more.