The Dark Knight + Scarecrow Question?

How come the Scarecrow has a small part in this one Becasues it sounds like his part is fading away and more focus on the joker and two-face. Will batman kill the scarecrow or lock him in arkham for good where he will not be any more Nolan Batman films. It's funny how he has a big part in Batman Begins, but not in The Dark Knight. He lived thru Batman Begins, so he chould have a big part in The Dark Knight as well to describe his conclusion.