The obvious next step is for Comcast to start a CDN inside their network and start selling CDN services to other companies, so that material served from the CDN

The obvious next step is for Comcast to start a CDN inside their network and start selling CDN services to other companies, so that material served from the CDN doesn't count against customers' caps. They can claim that this doesn't violate net neutrality principles, but the consequences would be the same: Comcast can use their ISP monopoly to keep their foothold in the content delivery business. The real danger to the open internet will come when wireless carriers get in on this action. Since nearly all wireless data plans offer tiny amounts of bandwidth as compared to wired broadband, there's a much greater incentive for users to use services that won't count against their caps...