In that case-
-Invites across the board.
-Significantly reduce button presses required to join chats etc. (context sensitive button prompts?)
-interactive notifications. Eg hold button to join.
-player met list is redundant due to how old the list of players is.
-report players. Mute players et al
-greater/faster/smarter profile customisation.
-YouTube upload/stream/app
-playstation wall; players can post screenshots, videos and comments specifically for your attention. (Like LBP hub)
-spotify and equivalent services- streaming spotify from device to ps4 at the very least.
-automatic gameplay broadcasting; no need to activate every time.