In the Star Wars Coming to PS4 segment of their DF direct, DF was speculating about what other next gen only games could be ported to last gen consoles. They said Ratchet is probably a no go. They also brought up Flight Sim which is another CPU bound game.
That got me thinking, of the few next gen games released so far, what do we think is impossible on last gen consoles. I agree with Ratchet because even though HDDs can run it and the PS4 equivalent GPU in steamdeck seems to be able to handle the graphics with some upscaling, their seems to be a big CPU requirement for the loading portal sections. Especially when running it on an HDD. Gotham Knights could probably be ported without coop requirements.
FF16 is an interesting one. They drop to 720p just to hit 60 fps during combat encounters. They drop to 1080p to maintain 30 fps at times in fidelity mode. PS5 has 5x more tflops and roughly 7x more powerful gpu. This thing might need to drop at 480p to run at 30 fps. A little more if they turn off RT shadows which they were rumored to be using. I dont see anything ssd wise that could be holding it back.
Dead Space has a little more headroom, it targets 1080p 60 fps though drops to 960p at times.
Star Wars requires SSD on PC. Has huge levels. Runs like shit in koboh where its severely CPU bound. Game runs fine on a series s at 900p without RT so with RT off they might get it to run at around 640p-720p on base ps4 after lowering some settings.
That leaves Starfield and Spiderman, both of which were dropping to 1296p in their demos. But starfield might be more CPU bound. Spiderman can also turn off RT reflections which should give them a big boost, but the faster flying speeds might make it pretty much impossible on PS4. We saw the game freeze up on PS4 when you could glitch the faster flying speeds.
Demon Souls should definitely be possible on PS4 at reduced settings at 30 fps. 900p minimum. Returnal seems to be broken on Steamdeck so might not be possible on PS4 but in terms of visuals i dont see why not. Maybe their engine doesnt scale well with last gen GPUs.