Recently Playstation CEO Jim Ryan confirmed Sony's intention to go all out on PS5 exclusives that are actually exclusive to PS5. Sounds good. No problem with newer PS4 games being developed to be also playable on the PS5, but I think PS5 exclusives should definitely be playable only on the PS5. Seems like Sony feels the same.
As for MS feeling the same concerning the XSX...not so much.
From the article:
"Sony is not planning for upcoming exclusives to run across both the PlayStation 5 and PlayStation 4, according to PlayStation CEO Jim Ryan.
Speaking to GamesIndustry.Biz, Ryan was asked whether Sony is planning on a strategy similar to Microsoft with regards to supporting exclusives across two generations of hardware. Ryan explains that Sony has always believed in generations, and that software should represent that new capabilities of new hardware. As such, Sony is not planning to make upcoming PS5 games compatible with the PS4, with Ryan saying that Sony plans to deliver software that can only be enjoyed on its new console."