I think self driving research has already benefited cars substantially via driver assistance, like you say. Recently I was in a base model Toyota rental (camry or corrolla I think) and was surprised when it automatically warned me that someone was cutting me off in traffic, before I even noticed them move a few car lengths ahead. Then I noticed there was automatic radar cruise control built in, which made the rest of the drive much nicer. I hadn't even looked too closely before since I assumed that tech wasn't pervasive enough yet to trickle down to a basic rental car.

I think that the technology is probably already saving lives - Volvo is trying for zero fatalities right now, and I think driver assistance will reduce the lethality of cars substantially before we're able to adopt self driving vehicles, which would likewise make it less of a disaster if we aren't able to adopt self driving vehicles in the short timelines originally predicted.