Ecclestone:
The protesters don´t need to resort to violence. All they need to do is stand on the road on the way to the circuit, with placards, and they would get their message out there. Nobody´s going to shoot them. If I was the organiser I would wait until 4 pm, or whenever the race starts blocking the road, a few thousand of them, and then go home. And if they successfully delay the race then they would get more coverage than they could dream of.
That could indeed be one possible strategy. With security forces deploying all kind of lethal weapons the tactic may become easily violent even if there are no intentions by the protesters.
It would be equally possible that protesters would take to the track once the cars are running and that would also be very dangerous indeed.
The sane thing would be calling off the race and running a replacement.