Although Sony has reversed its decision to release its games on PS5 exclusively, by announcing that Horizon Forbidden West and Miles Morales will be available for PS4 as well, it seems that this does not apply to Ratchet & Clank: Rift Apart.
This was evidenced by the tweet that Insomniac Games posted in response to a question from one of its followers this morning.
@insomniacgames Hey guys, I'm not sure if you've already announced this but I was curious. Will R&C Rift Apart be coming to PS4 as well or just the PS5?
— MC DC (Sidharth) (@Spidey889) November 2, 2020
And if you don't know, this new Ratchet & Clank game relies on PlayStation 5's ultra-fast download feature to transport players to other worlds in-game and download them in less than a second.
In order to implement something like this on the PS4, not only will it re-work from the beginning specifically for that version, but it may also change the vision of the main game director, which will be reflected in the target gameplay experience in turn.
It is reported that Ratchet & Clank: Rift Apart will run in dynamic 4K resolution on PS5 in normal mode.