Sony revealed the full PS5 specs this morning including the CPU, GPU and an insanely fast SSD which will remove load times for games, but in terms of backwards compatibility, Sony confirmed PS4 backwards compatibility, but were a little less than clear about how far this would go.
Mark Cerny, who is the PS5 System Lead Architect, said that they’ve taken the “top 100 PS4 games by playtime and they’re expecting most of these to be playable at PS5 launch”
This is apparently due to the fact that the PS5 is too fast and PS4 games require tweaks and testing on a case by case basis.
It’s unclear if Sony will keep adding to this list, but it’s fairly obvious at this point that there won’t be backwards compatibility outside of the PS4.
Lastly, we’re excited to confirm that the backwards compatibility features are working well. We recently took a look at the top 100 PS4 titles as ranked by play time, and we’re expecting almost all of them to be playable at launch on PS5. With more than 4000 games published on PS4, we will continue the testing process and expand backwards compatibility coverage over time.
Clarification: "Most" of the top 100 played will be BC on launch. Cerny explained the PS5 is too fast for some PS4 titles and they'll require tweaks and testing on a case by case basis.