It's hard to see how RBR/Vettel can lose this now.
Even Webber is getting decent results now and is in joint 2nd place (in the WDC).
It appears that the McLaren doesn't do too well in hot climate.
If Vettel were to not win another race this season, he would probably still end up winning the title.
If Vettel were going to be stopped, McLaren and Ferrari would need to keep Vettel off the podium for the remaining races, but I just can't see this happening right now.
Who knows though, at Silverstone new rules are being introduced, so it may have an effect on RBR's dominance.