I would say that RPP is a bullshit solution to the wrong problem. People are going to have cars, for some people mass transit isn't a good option (think old people and stair cases and long walks late at night in the winter), and some people will always drive no matter what because that's just how they are.
I don't think we should punish people in Manhattan, Brooklyn, and Queens who own cars any more than we already do. It really sucks to own a car here. I've personally been reducing NYC's debt burden with street cleaning fines. I never use the damn thing, I love mass transit, and I love my bike and walking. I'm relatively young (for now) and spry, what can I say.
But, why are we actually talking about ways of reducing commuter travel by car to the city when we're reducing MTA service at the same time? You can't keeping cutting back service on the G line and expect people to not drive from Brooklyn to Park Slope. How the hell are you supposed to get around? MTA service in Brooklyn sucks, entirely, and it's getting worse. That's why people have the cars to begin with.