It's not yet even sure who is going to win the 2012 F1, as this won't be finished until late November, so of course the winner of the 2013 championship is impossible to predict. In the 2012 F1, though, the likeliest winner at the moment looks like Sebastian Vettel from the Red Bull Racing-Renault team. Vettel has been the winning driver five times so far this year, more than anyone else (the next is Lewis Hamilton from McLaren-Mercedes, with three wins). The full results will be known after the last stage of the competition, in Brazil on 25 November.
So Vettel is also a strong contender for 2013, having already won in 2010 and 2011 and looking as if he could win in 2012 as well. He is still only 25 and in 2010 was the youngest ever F1 champion, so even if he was less successful next year he would have every chance of winning again in the future.