In fact, there’s already an example of this in the DCU. Batman appearing in Creature Commandos is exactly this. They don’t know who is playing Batman yet, nor what the specific story of his film will be, but they know they are going to make a Batman film. Batman is out there. So that’s why that got a tease.

James Gunn recently gave a group of reporters a status update on the DCU at a DC Studios presentation. Among many other tidbits revealed, we learned that Gunn is already hard at work scripting the next DCU movie he’ll direct after Superman.

Gunn said he's bringing key lessons in franchise building from his time at Marvel to DC Studios, with a strong focus on script quality over release dates and building a connected universe that still allows for standalone stories.