Announced in the Forums section of WB Games’ website, staff member Steven Grayson told the community that the game would be delaying the collection:

Batman: Return to Arkham was originally announced last month with a release date for July 28th of this year.

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."