I think there will be a lot of cameos in this one I hope and calendar man has to have a bigger role in this . It's Christmas eve
I doubt it. If you read "The Long Halloween" Calendar man has nothing to do with it and only makes a cameo .
So since its assassin based I'm assuming League of Assassin's are going to be prevalent, so probably Ra's Al Ghul will be behind it all and uncovering Batman being Bruce Wayne. However doing that pretty much means its taking a page from Arkham City's story