PS4 crossplay is for select third-party content only, according to Sony Interactive Entertainment. The company confirmed that only limited games will have this feature and it is starting with Fortnite. More games will be announced in the near future and we are expecting one of them to be Black Ops 4.
While Treyarch has confirmed that there will be no crossplay in Black Ops 4, it was prior to Sony making changes to its PS4 crossplay policy. Blackout mode crossplay would be perfect to have.
Following a comprehensive evaluation process, SIE has identified a path toward supporting cross-platform features for select third-party content. We recognize that PS4 players have been eagerly awaiting an update, and we appreciate the community’s continued patience as we have navigated through this issue to find a solution.
An open beta for PS4 crossplay is currently underway that allows gameplay, progression, and commerce across PlayStation 4, Android, iOS, Nintendo Switch, Xbox One, Microsoft Windows, and Mac. The beta lets Sony test this newly implemented feature before final rollout.
Some features are yet to arrive though; account merger will hit in November while it would take a few days for the ability to unlink ghost accounts from Epic Games. Many created ghost accounts to play Fortnite on PS4 and linked them to Epic Games account. These can now be unlinked to attack to your main account to PlayStation.
Sony banned PlayStation Fortnite accounts used to play Fortnite on other platforms. Players used ghost accounts to link with Epic Games to avoid having their main account banned by Sony for accessing Fortnite on Xbox One, Nintendo Switch, and others.
Thankfully, this will no longer be a problem.
PS4 crossplay has been one of the most demanded features, it was right up there with PSN name change; which by the way is expected to arrive by the end of the year.
Source: PlayStation Blog