Of course there are state laws and of course cars could brake or slow down and of course the occasional douchebag roadie could smarten up and stop triggering road rage. But I doubt it's going to change driver behavior. Whenever I'm on two wheels I assume I'm invisible to all the drivers except the ones who want to kill me.
One thing that frightens me is the difference in driver behavior when I ride with a safety message jersey - e.g., "DON'T RUN ME OVER" or "THREE FEET, IT'S THE LAW." Those get me a half-lane or full lane of clearance from 9 out of 10 passing cars. It's not like I'm invisible otherwise - bright jerseys and blinkies galore. But if I don't literally spell it out, drivers don't get it, and only 1 out of 10 would give me that clearance.
PS - Garmin Varia rear radar system = best bike $$ ever spent.