So this is interesting.

There is an easter egg in the Arkham Knight Batgirl DLC, A Matter of Family hidden away in a vent. Take a look at this video and you'll see what I'm talking about. This comes from Youtuber Dribbiz:

Yes. Starro appears to be sitting in a tank. I'm sure everyone here knows, but if you don't, Starro is the first enemy that the Justice League ever faced off again back in Brave and Bold #28. Could that be foreshadowing to suggest a Justice League game is on its way? On its own, I'd say no.

But this DLC was handled by WB Games Montreal, not Rocksteady. Now, if you remember, a supposed leak hit the other week about a Superman game coming from the Arkham Origins developer. But what if this wasn't just a Superman game, but a Justice League one? That was never substantiated, but I am beginning to see a certain picture when I tie these things together.

On top of that, job listings were found a while ago saying that the developer was planning to make an open world game next and that studio was made to create DC Comics games exclusively.

I may be down a rabbit hole of my own speculation here, but right now, I'm getting more and more convinced that this game is coming from WB Montreal. I'll continue to look. We will see what happens in the future.