You'd think this would've been done much earlier, but according to Eurogamer, Sony has been telling developers that any PlayStation 4 game submitted for certification after July 13 must also be compatible with the PlayStation 5. However, if a PS4 game receives a patch or a remaster after July 13, PS5 compatibility is not required but still "strongly recommended".
Sony is going through games "on a title-by-title basis to spot any issues that need adjustment from the original software developers." It definitely explains why only PS4 games have been confirmed to support the PS5, with Sony stating that the "overwhelming majority of the 4,000+ PS4 titles will be playable on the PS5." It makes sense, as finagling support for older PS4 games would be a lot easier than ensuring the original developers or publishers support for PS1, PS2, or even PS3 games on the PS5.
To contrast, Microsoft's support for older games will include HDR support, 4K resolution upscaling, and support for the Quick Resume feature that current-gen Xbox games will be able to support. This support will go as far back as 20 years ago to the original Xbox.
While support goes back on the Xbox Series X over two decades, the closest thing Sony has to that is the PlayStation Now service, which allows players to play older PlayStation games and will most likely be included on the PS5. So... older titles are sort of supported, I guess?
This is a large difference compared to Xbox' approach to backwards-compatibility, which Microsoft bragged to be "the most powerful and compatible next-gen console with thousands of games at launch." From the looks of it, Microsoft's continued approach going into this generation is that it's their responsibility to ensure that their console is the Xbox console where gamers can play all/most of their titles from all Xbox generations on a single console.
So, for all PS4 games that are sent in for certification after July 13, 2020, they will have to support the PS5. Eurogamer has heard that The Last of Us 2, as well as Ghost of Tsushima, despite being through - or about to go through - certification, will be supported on PlayStation 5. Basically, games sent in for certification are a process of submitting the game to the platform holder (PlayStation or Xbox) for review, and is done well in advance of the game's launch.
What do you think of this news? Do you think Sony is making a mistake by not including compatibility for the PS1-PS3? Let us know in the comments!