I think the best solution is to look at problem pubs and nightclubs - assign plastic to those who have higher than a set amount of injuries, and those who are in trouble-free areas still serve glass.
EDIT: Of course, the root problem is society.
That wouldn't make a difference. I was in a bar a few years ago with a group of friends and some woman who was arguing with an off duty police officer started throwing our empty glasses across the room at her. She hadn't actually had anything to drink in the bar and we'd caused no problems, clearly she shouldn't have been around glass

The idiots who attack others with glasses should be banned, not the glasses.