Broadband economics

BusinessWeek: “Researcher Yankee Group estimates that the average monthly operating cost per cable-modem customer, which includes billing, maintenance, data-transport fees, and network management, totals $15 to $23. At $45 per month, cable operators’ operating margins are 35% to 45%. If the price of an always-on connection dropped to $25 or $30 a month, those margins would essentially evaporate.” Not sure I follow that last step.