Time for some championship math
1) Sebastian Vettel 259
2) Mark Webber 167
3) Fernando Alonso 157
4) Jenson Button 149
5) Lewis Hamilton 146
That's a 92 point gap between Webber and Vettel. Even if Webber wins all of the last seven races, Vettel would only need to get 4th in every race to remain the leader (final total Vettel: 343, Webber: 342). And if Button wins all of the final races Vettel only needs to get 5th places (final total Vettel: 329, Button: 324).
Vettel can now afford to score no points for three of the seven remaining races and still have (at least) a 17 point gap.