Microsoft is already swinging all over the place with the Xbox Series X backwards compatibility and a Sony patent seems to suggest they are working on something similar, although there are some doubts.
Sony's patent suggests that the games from PlayStation, PlayStation 2 and PlayStation 3 can be stored and used with the cloud gaming library. Technically, this was already known since PC players have been emulating console games for a long time now but since this is Sony's patent in question, it would be somewhat new for the consoles.
A further interpretation by Renka_schedule on Twitter noted that there is a mention that the games can be run on a virtual machine that mimics the operating system associated with each game console. Again, this was proven to be possible by PC users and further hints that Sony might want to utilise emulation in order to run older games on PS5.
However, there is a hitch. The patent was submitted a long time ago and one of the credited inventors already left Sony in 2017, which could mean these were the plans for PS Now.
Even if it is related to PS Now, this still means Sony has the ability to provide players with some sort of backwards compatibility but it remains to be seen what the company will do about it.
It would be fun to boot up a next-gen game, get nostalgic and then install Snake Eater. One has to wonder how it held up over the years.