Even if it does have the larger battery I assume it'll only be there to compensate for the retina display and/or the new A6 SoC. I doubt Apple will put it in to increase the already good battery life by an hour or two.
I agree. When we look at the transition to the iPad 2, Apple had the chance to increase the battery life by maintaining the same thickness. It seems clear that they have a 10 hour goal and they will make it as thick as it has to be to keep that number.