Comcast taking two steps back Until three or four years ago most regular cable/dsl customer products had ridiculously low traffic limitations (and I'm talking about 2-10GB) - here in Austria. It has only been the past couple of years where competitive companies offered alternative products and prizing on the market - it finally got competitive enough to allow unlimited/flatrate options for all customers.
While I personally believe that the limit of 250GB download traffic is high enough for now, it's difficult to predict how long that will be the case. Don't even get me started on the high prizes for overshooting the limit, 1.5$ per GB is at least 15 times higher than the wholesale prize for international traffic and Comcast's own cost is probably well below that figure.
The past few years were marked with plenty of new multimedia content or modified content in higher bitrates/quality that made Internet traffic grow exponentionally, there wasn't even piracy included yet. For example: my own traffic has multiplied in the past few years, from about 5gb per month in 2005 to at least 50gb in 2008 without doing many things different except using more multimedia content where it is available and where it has become a direct rival in terms of quality, like music/radio. I've never used any filesharing application but since music streams are available in bitrates of 192kbps upwards, my time listening to streamed content has increased.
To make a long story short: I see no end to the naturally increasing traffic in our Internet and while limiting piracy is an acceptable (and sometimes admireable) goal, it's indeed a dangerous road Comcast could go. In two or three years these 250GB could be reached already for a considerable group of users who like to enjoy (legal) multimedia content and may be playing online games on the side. Consider that home connections are increasingly used by the whole family from their own pc's too.
A final note which is completely theoretical and mathematical: considering that 14k users are likely to be affected by this new traffic limit, Comcast would save a total traffic of 2.67pb (2,734tb) per month if we assume that each of those 14k users presently downloads 500gb per month. It sounds like a lot but in relation it's no more than a tiny grain of sand: 2.67pb means that each comcast user would need to download a mere 203mb to be back where they started. Those are values that will easily be reached by a natural progression within a few months.