Specifically, any developers sending games to Sony for certification after 13 July will have to meet this new requirement. This means that games submitted after said date will have to not only run on both consoles, but also have the same features. The company said that it will contact devs individually to give details on testing for PS5 compatibility. It’s important to note that certification happens a lot earlier than release. This means that games like Ghost of Tsushima, which will be released on 17 July, will not need to be forwards compatible with the PS5, though the option remains open.
This move by Sony is quite the opposite approach to Microsoft’s Xbox Series X and its Smart Delivery program. This instead allows next-gen games to run on current gen consoles. Xbox is also not as strict with the program, making it only mandatory for first party games. In other words, this means that games that are PS5-exclusive will remain so. But newer PS4 games, on the other hand, will also be playable on the PS5. Sony is likely looking to encourage early adoption of the PS5, by making it able to play new games for both generations. (Source: Eurogamer)