Hearing from multiple sources that Rocksteady pitched a Superman game to WB as a follow up to Arkham Knight, and WB passed on the project.

Judging how similar this feels to the “New Gotham” section of Arkham Knight, this could be for that.

The various Easter eggs in Arkham Knight referencing Superman and Metropolis were meant to be hints towards the story and characters.

https://kotaku.com/batman-arkham-knight-is-full-of-superman-easter-eggs-1713662331/amp

I’m sure people remember this Easter egg the most:

The destruction tech used in Arkham Knight was also something that would’ve transitioned to their Superman game.