It's already been said, that the lack of adjustable front aero, will lead to serious instability problems as the race goes on, as the characteristics of the cars will shift wildly as the fuel loads get lighter, something that this year, drivers were able to compensate for as the pit wall dictated. Next year however, no adjustable aero, will mean that driver skill will become more important in holding the wibblywobbly cars on track.
Personally, I think that will play against Vettel, who seems to only really be comfortable when he is out in front with a car that is a class apart from the rest. Which I don't see the RB being.
My money is mostly on Hamilton/Alonso, who are without doubt, two of the best drivers out there, and I think that Button will continue to do well, and be slated by people here who will never accept him as being anything other than 'average'.
As a rank outsider, Kubica could have a good year if Renault give him a good car, and I'd like to say Kobayashi continue to develop as he seems to have the killer instinct that most modern drivers are lacking.
What I really would like to see, is an end to the "Okay, go to yellow 4, save fuel.." from about lap 3.. Force all cars to start with enough fuel on board to complete the race.