In my original post on this subject (yesterday - 4 posts up from yours) I stated: "Broadband internet - sunk cost (assumed to also be used for other things)"
If/when broadband providers start to enforce caps (currently my DSL through my local telco has no cap) that has the possibility of changing the equation. I don't typically plan much for possible future changes of this nature (lumping pay television and internet costs in with utilities such as gas, electric, water, etc) - I focus on the present cost of the bill and what I can do to reduce it. Others may well choose to take a different view. I don't see a possible future cap as a reason to not extract as much as I can now for a lower cost.
some cable companies are already enforcing caps, telcos are starting to phase out dsl. you might want to look to the future for tomorrow you may get a disconnect notice that your Telco is shutting down dsl