The developers who will publish their games on PlayStation 4 in the coming months they will have to make sure they are compatible with Playstation 5, now close to announcement.
According to what collected by Eurogamer, on the internal portal for Sony partners you can read that from 13 July all games that want to be accepted for distribution on PS4 must not only be compatible with PlayStation 5, but also ensure the same gaming experience on both consoles.
Again according to Eurogamer, Sony will take care of contacting the developers and explain to them how to test their games for compatibility with the new console. Developers will also be forced to maintain compatibility even after the game is released and will not be able to remove functionality on either console.
Games subject to this rule will be only those who will apply for approval after July 13, not those who will come out after that date. So any games coming out in the summer may still require a patch to run on the PlayStation 5.