A Warner Brothers staff member posted that Batman: Return to Arkham was delayed with no new release date to deliver a more polished experience.
You can find the full quote from the forums below:
After reviewing the progress of the project, the team at WB Games has decided to delay the release of Batman: Return to Arkham to give the team at Virtuous Games additional time to deliver a polished Batman Arkham game experience. We do not have a release date yet and will be sure to communicate that once we are sure the game will be ready. We know this is disappointing news, but we feel the extra time will allow the team to create the best gaming experience for our fans.
In order to keep conversations around this topic in one place, please keep any discussions regarding this news in this thread. All other posts regarding the release delay will be locked and directed to this post.
Batman: Return to Arkham is a remaster of Batman: Arkham Asylum and Arkham City for the PlayStation 4 and Xbox One. It was scheduled to release in July. It has no new release date.
Source: God is Geek