> In that case many of those would be Comcast customers, and peering would end up equal.
NOT HARDLY!
They would mostly be customers of small datacenters in various places all around the country, and thus, customers of Cogent and Level3.
Datacenters generally go for tier1 bandwidth, not consumer ISP bandwidth.
Look at the plans that they offer on their website. The fastest upload I can find is 20Mbps for $200/mo. http://business.comcast.com/internet/business-internet/plans...
That's $10/meg which is A LOT.
Three years ago if you were willing to buy in bulk, you could get bandwidth for as low as $0.65/meg as this HN user points out. https://news.ycombinator.com/item?id=3892854 Based on his comments I suspect that you could get it for less than $0.50/meg today, maybe less than $0.25/meg.
Sure looks like Comcast wanting to have its cake and eat it too.