This is what I think that what's going to happen on Pokemon Black and white (I'm not saying it's going to happen) but this is what I researched for the whole 3 years:
There are going to be:
12 normal types
6 fighting types
12 ground types
11 rock types
16 bug types
9 ghost types
20 grass and water types
26 psychic types
7 ice types
The gym leader are going to deal with
rock, water, electric, bug (REVEALED!) and psychic (the rest not sure but could be either {steel or dark})
The elite four are going to deal with
ice, ghost and dragon (others not sure but could be random)
There is going to be at least 4 event legendary Pokemon
There are going to be:
12 normal types
6 fighting types
12 ground types
11 rock types
16 bug types
9 ghost types
20 grass and water types
26 psychic types
7 ice types
The gym leader are going to deal with
rock, water, electric, bug (REVEALED!) and psychic (the rest not sure but could be either {steel or dark})
The elite four are going to deal with
ice, ghost and dragon (others not sure but could be random)
There is going to be at least 4 event legendary Pokemon