This is what I speculate will happen in B/W, whether it already be confirmed or not.
-These games will be 3DS ready. It is confirmed that they are not.
-There will be about 120 new pokemon.
-No eeveeloutions (I can only hope).
-No new types. I REALLY hope that they don't make new types.-Downloadable content, but not much since this will be a new feature for any DS game, to my knowledge.
-Dark type gym, finally. I hope for this as well.
-More/Less than 8 gyms, if you look at the Isshu map it's hard to tell where towns are, so I couldn't count exactly where the gyms would be. Why? I think they should just stick to the traditional 8 gyms.
-Deeper storyline, maybe focusing more on the character's background, or getting more in-depth with the gym leaders and the E4. Something I hope for as well.
-Hopefully not the same "TEAM WHATEVER!!!" B.S. we've seen for the past 4 generations, and instead just one villain or a small group of villians, hell, maybe even a natural disaster linked to the legendary dragons! I REALLY want the natural disaster idea to happen. Like the Isshu Region is going to be hit by many natural disasters and the legendary Pokemon are enraged or something.
If there's anything else I missed, I'll put it in another post.