what villians are left......
Well, this is the beginning of Batman, so it happens even before the 1989 movie. Scarecrow and Ra's Al Ghul are the villians in this one. I personally think the latter one could probably be enough for a movie, especially with Ken Watanabe as the character.
Scarecrow will be interesting, but I hope they flesh things out a bit if they're going the 2 villian route.
And there are some Bat villians left:
Dr. Hugo Strange
They could also revisit ones like:
Bane (he was underused in the crappy Batman and Robin)
Riddler (he's not dead)
Two-Face (is he dead or was that a double?)
Joker (same as above)