What we do know for certain is it will strip you as a consumer of control over of hardware and software that you purchased.
Nothing will stop 'piracy' - noting will stop any crime.
Copying DVD's required cost and labour. There's a limit to how much pirating any individual can do.
Over the net - it's rather instantaneous.
DRM'd content raises the bar beyond most people, so it cuts down on piracy.
All it takes is one individual to make a "DRM" free version of a movie and begin to torrent to the public - and then the bar is lowered to the average consumer / pirate..