Interesting. That technology deploys on impact; one could imagine a more optimal version that detects pedestrians with proximity sensors and inflates an airbag before the vehicle even reaches the pedestrian. (Obviously the car could also do automatic braking, but the airbag could help in situations where stopping wasn't possible.)

It seems like such an airbag could be used to lessen the impact of vehicle-to-vehicle collisions as well. Perhaps have multiple inflators so the car can select air pressure based on the projected force of impact.

Airbag suits are available now for motorcycle riders, external car airbags would kind of be just a larger (potentially more complex) variant of the same idea.