With this deal, Netflix has effectively cut out the middleman Cogent, and is sending traffic directly from their servers onto Comcast’s network. Not only will this mean better quality for Netflix customers on Comcast, but it also raises the barrier of entry for potential Netflix competitors. Netflix currently has unique leverage over Comcast due to Comcast’s proposed merger with Time Warner, which, combined with their brand name and favorability amongst customers and regulators likely meant they got a great deal; future Netflix competitors, forced to go over the open Internet or rely on providers like Cogent will be at both a cost and quality disadvantage.
This is very important for Netflix long term. As they continue to dominate the streaming video market, this is an extra barrier to competitors. Amazon may be willing to throw money at content, but are they will to throw money for "better" access to the last mile?