That's the ending presented to us by Arkham Knight, the last in the brilliant Arkham series of games from Rocksteady Studios. And that was the last we officially heard from both the developer and the Arkhamverse. Rumours began to circulate of a Superman game or a Destiny-style Suicide Squad title, but nothing ever came of them.
The most recent leaks indicate that Rocksteady is actually working on a single-player focused, co-op enabled, Arkham-style game that allows players to jump into the tights of the Justice League. Though still very much a rumour, this particular one has been around for almost two years now, and it just keeps coming back around from different sources. So, perhaps there's something to it.
Expected to be set before the Arkham games and building off the upcoming soft reboot of those from Warner Bros. Montreal, this game is said to vastly expand upon the Arkhamverse and pit the League against their first comic book enemy: Starro. This continually updated, games-as-a-service style, next-generation game sounds like exactly what fans want.
(Well, so long as they include these few things to really make it something special.)