It cuts the teen demographic in half. I suspect it would turn into a compromise for R's, with PG-13 still being the coveted goal for box-office smashes and R being the coveted roll for serious films. I could see it becoming a "We left in some more cussing" spot, but anything else is expecting much. It doesn't fix the problem, it just ads another layer to it. Sort of like saying, when your tire goes flat, that changing the tire is too unrealistic and it's better just to tape over the hole and see what happens.