the third part would probably have Riddler or Ra's al-ghul (he's never dead),along with a monster villain like croc or clay-face,but something tells me that nolan prefers the psychological villains to the physical ones .Another possibility is the introduction of Selina Kyle.
As for showing robin being murdered, we dont have to think about it for at least 3-4 more sequels,as they have to show Bruce adopting Grayson, him evolving into the Nightwing,and the subsequent recruitment of Jason Todd. too much stuff to show.what they can do is run with the combined story line of the long halloween and the dark victory in a compressed form(though that means theyll need a joker)
"The accumulated filth of all their sex and murders will foam up about their waist and all the whores and politicians will look up and shout "Save us!"...
....and I'll look down and whisper "no."
- Rorschach
