Many comic lovers know the origin of Hush. Hush is a childhood friend of bruce. Hush's real name is Thomas Elliot. His story started when he begen to hate his parents, and tried to kill them. He managed to kill his father, but his mother survived. Thomas was outraged at the family. Later that year at a summer camp he attacked a child and was sent to a phych ward. He later was realesed by an intern called Jonathan Crane, and went to the aid of his mother. When his mother fully recovered she disowened him from the fortune. So, Thomas killed his mother and recived the fortune. It is here were he plots his revenge on Bruce Wayne.
So here is how I thought he could be used. He could be a doctor that was trapped in the hospital when Joker blew it up. His face is horribly scared and he seeks vengence against Batman for not stopping him. He goes to the new crime lord in town, Black Mask. They partner up with the Riddler, a cop who becomes obsessed with batman and gives info to Black Mask.
The Batman 3 story arc could be similar to the Batman:Hush story arc. Now if one wanted to you could have Catwoman in this storyline, but even if the movie is over 3 hours i doubt 4 viilians is necessary.So, in the end we could have Hush as a primary villian. Finally, I must mention that on several occasions Chris Nolan has talked abut how one of his favorite villians is Hush(gasp).