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.

DC Studios, led by James Gunn, focuses on integrating key plot points into films instead of using post-credits scenes as teasers. Gunn emphasizes granting writers creative freedom and avoiding unresolved cliffhangers to ensure movie quality.

DC Studios co-CEO James Gunn has revealed that he has a plan for the universe, building to what sounds like a big finale. At a recent press event, Gunn shared that a six year plan has been mapped out for the DCU that will lead to an Avengers-style project (H/T Variety ). But, Gunn said, "each individual project works as its own thing".