I don't think we have to worry about the villains teaming up. They handled it perfectly in Batman Begins. There was Falcone, Scarecrow, Ra's. They each existed with their own purposes and methods. It worked great, and I don't think anyone should be parading against more than one villain in the next one. Gotham is crime ridden, it would be stupid to think each villain's gonna line up and be created at a time that's fitting for Batman's schedule. So whatever they do, I'm sure it'll be great. I feel like it's safe in Nolan's hands. I am interested in some things though. Like the Joker's casting and performance, there's a lot of ways you could go with that and I think there's room to create someone unseen before, that can be incredible to watch on screen and definitive. That's the potential. He's raised the stakes so high with Begins, the real challenge is not making something great, because I think he will, but something that will blow us away as much as Batman Begins.
About Robin, I haven't seen him done well and I don't really care to see him. Let it rest now, I don't see him appearing at least until the 4th one. There is a story set out for the next 2. We're not going to jump ahead years and years. Not when you have so much story to tell. I personally hope they just get the next tale done right and take it from there. You don't know how long you can string it until it goes bad after all. Why get to Robin now? I don't have that itch anyway. Also, I really don't expect Ra's to return in either of the next two. Again, not with so much story to tell. It was nice what they did with him. Just fantastic. But he really is a relatively smaller character on Batman as a whole. And as Nolan said, Batman Begins had to and did stand on it's own. It was never meant as the meat and lining of the whole new trilogy. It was just an interpretation of Batman's beginnings. And really, they did so much right with Ra's, there is no reason to go back. All threads were tied in that story. There's a lot more pressing stories and adventures for Batman in saving Gotham now.