Have you not seen the Remake of Crash Bandicoot? Or, is that not on the Playstation / PS4? I'm pretty sure that it is. If it's not, they're probably not making any new Crash Bandicoot games due to licensing issues, or possibly due to there not being enough new content that they could add or create with a new version of the famous character. Once there's not much creativity left on the table, they're going to suffer losing lots of money.
As well, Crash Bandicoot is not always going to be on a PS4, or any Console that's not home to that specific character, it's not a game series that's 100% console exclusive.