The .31 cents was based off a 500 million dollar settlement. It was used as a baseline because of the VHC v. Apple case where VHC was awarded 500 million by the courts last week. It was also estimated that between the 13 companies, there are far users with docsis 3.0 hardware compared to Apple phone users so you would likely see a much higher number awarded to chanbond in course
Chanbond is just making an example of those 13, because they are the largest. If they win/settle, all the cable companies in the country are liable for infringement and will be counted in on a settlement, if it goes that way.