McLaren can't win either title if Red Bull can get both drivers to consistently finish near the front. At the moment the RB drivers are alternating good drives with bad drives and that is preventing them from using the car advantage. Hamilton is leading the drivers' title race because he is finishing consistently well while the two Red Bull guys take turns throwing points in to the weeds.
Should McLaren ever get their car to within a couple of tenths of the Red Bull then they may be able to steal both titles from Red Bull.
If Red Bull can maintain the several tenths advantage they had in qualifying at Silverstone then they have no one to fear but themselves.
The title is Red Bull's to lose even though they are currently second in the tables.