Honest question. What is the deal with BC on the PS5?
I plan to get the PS5 DE "soon", so I can enjoy the great games I missed on the PS4 (and play next-gen games, of course). From what I gather, 99% of the PS4 games should work on the PS5, but are there any enhancements? If the games play as-is, without improved resolution or frame-rate, I might as well get a cheap PS4 and then wait a few years before buying the PS5. If I buy the games digitally for the PS4, I assume they will be available for me on the PS5 as well?
99% of the unpatched games will run fine, the games that don't will likely have issues to do with running on faster hardware.
For example, a PS4 game will be expecting to load assets in from the HDD at a slow speed, but with the SSD loading them in very quickly it may cause timing/race condition issues In the game.
That's just a very basic example, and there'll likely be more complex issues for some games, that maybe used an API/library in a non-standard way, or that were very optimised in a very specific way for speed of the PS4, etc.
The games that will be improved, without a patch, will be games using dynamic resolutions to reliably hit 30 or 60Hz, they should now run at the desired/intended resolution all the time.
Games that also struggled to hit their target frame rates should now be hitting them regularly on the PS5.
So when charging across a field in 64 player Battlefield 1, with tanks,, smoke, explosions happening all around you, and planes annoyingly dropping bombs onto you, the framerate probably won't be dropping down to 40/50fps on the PS5 like It did on the PS4.
Also, games with an uncapped frame rate, such as Hitman, will run at a higher frame rate on PS5, this will be great for monitors and TVs supporting VRR.
Although most TVs support VRR from 40Hz (LG) and 48Hz (Samsung?), so uncapped games will need to run higher than those minimums to get the VRR benefit there.
What you won't see is PS4 games magically jump from their normal (fixed) 30fps to 60fps on PS5, unless they've been patched to do so.