I'm excited about this, because yeah, it's this. However, some things I took away from the trailer (warning: wild guessing coming in)
Did anyone else feel like maybe Poison Ivy is...backing out? Not switching sides and helping Batman exactly, but she either didn't agree with the alliance, or she no longer wants to be a part of it, so she's giving Batman info to help him stop it? I could see this happening, because she never really came across as, "I'm out to get Batman!" in the other games, and I doubt what is happening in the city is good for all of her babies...
No sign of Catwoman? Man, I hope that doesn't mean that she's dead, or that she dies. I like her, and I loved playing as her.
I know everyone is saying that the voice in the trailer is Scarecrow, and perhaps maybe it even is (too lazy to go check credits), but what if it's not? What if the trailer is just shown that way to make it seem like he's the one talking, but we are actually hearing the voice of The Arkham Knight? As a few other people have pointed out, Scarecrow shouldn't sound that...sane, calm and collected. Besides, he was voiced by the same person, at least I think he was, in both games, and it would be really sad if Rocksteady replaced his voice actor for his big role.
EDIT: I did some quick digging and I didn't find anything that said for sure that John Noble is the voice of Scarecrow. I did find a sight that says it is rumored that he is, while everyone else is confirmed for their characters, but nothing about him being Scarecrow. I really hope Rocksteady is trying to pull a fast one on everyone.