The need to exempt various types of traffic for business reasons is ultimately why I think monthly data caps will fade away for cable/telco-provided Internet service.

An example would be some provider like Disney saying that in order for Comcast (or some smaller operator) to be able to carry their TV channels they must also zero-rate streaming from their sites. Or Hulu and Verizon do a deal in which Hulu content doesn't count toward a cap on Verizon phones. These things are becoming more common, and I think the difficulty of figuring out which bits count and which ones don't (especially when they all come from the same CDNs) will prove to be more trouble than it's worth.