I would think, at least, for PRIVATE games on your own ded server it would be allowed cross-platform, given the focus on Co-op. I have a lot of friends at this point, though, who have a PS4 and haven't updated their PCs in some time. However, we've been running dedicated servers for KF1 since 2010, and generally only play private games, which I have no doubt will continue with KF2. While I think it'd be great for those in general lobbies to be able to cross together, I can see where at least PS4 and PC players might be separated for games that involve matchmaking. Forgive me if someone mentioned this awhile ago, but afaik there's no definitive word yet as to whether PC and PS4 will support cross-platform multiplayer.
