Points after 14 of 19 races run:
Mark Webber - 187
Lewis Hamilton - 182
Fernando Alonso - 166
Jenson Button - 165
Sebastian Vettel - 163
Tracks left: Singapore, Suzuka, Korea, Interlagos, Yas Marina
Webber is looking very cozy after getting back the championship lead, and the Red Bull should be utterly dominant at the next 3 tracks at least. However, if Vettel (who is naturally faster than Webber) can pull himself together for a final charge he could beat Webber in a couple of races and take vital points from him. I don't think he will win the WDC this year after all that has happened but I think he will be a spoiler.
Hamilton IMO has had the best combination of speed and consistency out of the top 5, but a DNF this weekend when Red Bull was off the pace would have killed his title chances if his car doesn't get up to the speed of the Bulls and Ferraris in the next few races. I think his car might challenge for a win at Yas Marina with its long straights, but by then it might be too late.
If Alonso stops making mistakes and his car can stay close to the Red Bulls and ahead of the Mclarens, he could have a chance of leapfrogging Hamilton at least. But Ferrari isn't the ultra-efficient winning machine it was with Schumacher and the dream team, so I wouldn't bet on it. I think at least one more thing will go wrong for Alonso.
As for Button, I don't really see how he can defend his title. The most he could hope for is to leapfrog Lewis if Hamilton has a couple more no-scores like today, but I don't see Lewis' luck taking such a downswing. And as I said earlier with Lewis the car may or may not be up to it.
So, at the end of the season I think Webber will win, however it's so competitive and there are so many variables that will come into play: the cars' form, the drivers' form, the weather, the tyres, the other drivers, the stewards, inter-team politics, and that magic ingredient, luck.
What do you think?