A screenshot of the villain Hush has been posted on the official Batman: Hush Facebook page with the caption: "Remember a little appearance by somebody in Arkham City? Well things may be abut to get more interesting next month..."
Serial killer Hush, formerly known as Dr Thomas Elliot, had a cameo in Batman: Arkham City, and we can definitely see him as fully fledged villain material for the next chapter in the Arkham series.
Until this new title's reveal, we can look forward to the next DLC for Batman: Arkham Origins. We generally liked Arkham Origins, though were disappointed to hear that its bugs are not likely to be fixed.