I played the demo on my regular PS4, seems the game is not very penalized on obsolete HW, Pony has already said that ps5 will run ps4 games, probably SE will just make a patch for nextgen to finally support 4k and 60fps....
pony? Is that a youtuber?
But yes, it's probably better of me to say it's more than just running ps4 games. You probably know all this, but I feel like breaking it down
There are different ways of implementing backward compatibility. There's hardware, software, and a mix.
- Software being difficult and requiring an emulator of the original hardware, which is how ps1/ps2 games are done on the ps4.
- Hardware runs the code without faking old hardware, just limits the hardware to the specs of the original (so, slow down the cpu or limit cores to what was available for old hardware, etc, which is what the Wii and Wii U did for gamecube/wii compatibility). This can include adding in old hardware to new hardware so everything will play (ps3 original took this approach).
- A mix will have some variety of code run off hardware, and some of the hardware emulated/faked. There can be overlap and sometimes a "hardware" backward compatibility isn't 100% hardware but it's close enough.
PS4 on PS5 should be completely hardware. It'll be more like playing xbox 1 games on xbox 1 X. They should be able to run PS4 games better and smoother than they played on the PS4 as there will be little to no overhead. And games with code which is aware of the better resources available will be able to play better.
tl;dr: It's probably easier to think of the ps5 as the ps4 extreme, in regards to compatibility, rather than a completely different beast.