Drivers on a "final warning" over crashes. Nothing given away as to what happens if they do crash, but I wouldn't be surprised to see a driver taken out of the car for a race. That would focus their minds massively. If Hamilton is "banned" for a race then Rosberg wins the title (all other things being equal). If Rosberg is banned for a race, then Hamilton would use that opportunity to minimise any grid penalties for a new engine.
The big question is: who decides when the penalty clause takes effect and what triggers it?
http://www.bbc.co.uk/sport/formula1/36733390