"[T]he biggest challenge for the exchange operators is to convince private-sector employers of the long-term benefits and cost savings of delivering health-care benefits through the exchanges and help them overcome concerns about the potential loss in employee productivity and morale as well as the stringent reporting requirements.... [P]rivate exchanges aim at serving an estimated 140 million participants (15 million retirees and 125 million active employees) who are currently covered by employer-sponsored plans.... Future opportunities for the insurance brokers and exchange operators are the estimated 30 million retirees who are not in employer-sponsored plans and are ineligible for Medicaid as well."