Alrighty, then. 12 new pokemon who have not been explained, with only nine having names so far. If anyone else hasn't noticed, this is pretty unorthodox of GF to do this. In total, we have seen 26 generation V pokemon. Let me bring up some statistics here.
RBY: 146 non-legendary pokemon
GSC: 92 new non-legendary pokemon
RSE: 128 new non-legendary pokemon (pre-national)
DPPt: 74 new non-legendary pokemon (pre-national)
Now, I think we can all agree that the pokemon revealed thus far do not look like evos or pre evos of existing pokemon (although some wish to argue that Munna is baby Drowzee =|). As stated many times, Nintendo is calling Black and White the "rebirth of pokemon". And as per the numbers above, the ammount of new pokemon in generations I and III far exceed the other two, although generation would obviously hold the highest number of the four.
From this, I feel (and hope) that there will be a lot of new pokemon and that the Isshu Dex will not be filled with zubats, geodudes, abras, tentacools, machops, magikarps, goldeens, weedles, wurmples, nor any evos or pre-evos of existing pokemon. Personally, I wouldn't mind Koromori replacing zubat in caves (please please please).