> It will always be the case that circumstances can change faster than something with the momentum of a fast moving car could adapt. Somewhere between "you're boned" and "your car saves the day" lies room for a scenario such as this, with potential room for a large amount of thinking.

I think it's possible that with improving AI of self driving cars, making overall safety better, there will be ≈0 occasions when car simultaneously 1) doesn't have time to react to some sudden problem and 2) has time to make informed decision (and physically perform it) on how many people to save. Especially if pedestrian airbags become popular.