I hear what everyone is saying with the Ferrari being unproven in the new regs to truly make a "competitive" car. But I think it's difficult to say with 2014 on the cards, in honesty. The engines are a big question mark, especially after engine makers are contemplating raising the price of engines sky-high due to development costs, including Renault. With that in mind the only proven consistently "top" team, with a consistently good engine, will be Ferrari.
I hear what people say about Vettel getting stomped by Alonso, and I can see why some say that. Personally I disagree though - I think they're both going to be very close, if this indeed does happen, and in fact too close to call. Whoever beats the other (given equal reliability) will only do so by a slim margin IMO.
Also I hear what people are saying about them not wanting the other in the same team, as that would mean taking points of each other. But with the grid so close, or one as close as 2012 so far, would it really matter? The idea of having a patsy driver coupled with a world-class driver is so that the patsy one doesn't take points off the world-class one when the car is strong. But when the field have cars that are more or less equally competitive in all cars - then that scenario holds no water, really, because everyone is practically in the "same car" when it comes to competitiveness.