The whole point of the DC Extended Universe is that it's modelled on the comic books. In the literature world, these characters inhabit the same world, crossover with one another, and have been doing that for generations.
Sure, there have been reboots, restarts and temporary cancellations over the years, but it's still the DC Universe, with the same legacy underpinning it.
What if the movie franchise ends up mirroring the comics in this sense? There may be a few changes and rejigs here and there, but as long as the films are profitable, they could maintain a sense of continuity indefinitely.
This sounds like it could be the plan for the Marvel Cinematic Universe, which will wrap up the story it's currently telling in 2019's Avengers 4, before spinning an all-new tale in the movies it has lined up after this.
If Spielberg is wrong and the superhero bubble remains intact, there's a possibility the DCEU will continue to churn out inter-connected films for the next lifetime.