A few months ago we finally learnt that Gotham Knights is due to launch on Xbox this October. At present, the game is confirmed to feature two-player drop in drop out co-op, however, a PlayStation Store description shows the plan may have changed.
The PS Store listing now says that Gotham Knights will support four players over network play. That same listing also says that the game "supports up to four players with PS Plus", so clearly, the plan seems to be four-player co-op in some capacity.
However, these store notes don't detail any actual game modes, so this could elude to a separate co-op experience to the main campaign. As we mentioned previously, the main campaign is currently slated to include two-player co-op support.
We may find out more on this little discovery tomorrow, May 10th. Warner Bros. has announced that it'll be showing more of Gotham Knights on that very date, at 6am PT / 9am EDT / 2pm BST.