Why your company health benefits may change - CNBC.com

Despite his and Parry's uncertainty, two factors are spurring the move toward private exchanges.

One is the opportunity for companies to save money by outsourcing the administration of health benefits to the exchanges, and from price competition among insurance providers offering plans on the exchanges.

Extend Health, the Towers Watson private exchange that now will be handling Medicare plan options for 110,000 IBM retirees, estimates it can save clients "3 to 10 percent per year" in costs, said Bryce Williams, who leads Extend Health.

(Read more: Red states could beat blues in Obamacare exchange enrollment)

Extend Health currently has about 300 companies as clients, the "vast majority" of whom enroll only retirees, Williams said. But, he noted, "three major companies are going to join our exchange this fall," bringing about 50,000 of their active employees into the exchange.

The other factor generating increased interest in exchanges is that "increasingly consumers are more prepared, more expectant of having choice and retail-like experience when they're buying health insurance," said Birhanzel of Accenture. "The theory is that people, over time, are going to choose benefits that best suit them."

He and other experts noted the tendency of many people to "buy down" on the exchanges—opting for plans with lower premiums, and thus saving money on their short-term health costs by accepting higher deductibles and smaller health-care networks.

That tendency means that in some cases, the employees' costs for coverage remain unchanged or less than before, even if an employer is offering less of a subsidy for the exchange plans than it had offered under the traditional company plan.

"It is a win-win most of the time," said Alan Cohen, co-founder of Liazon, operator of Bright Choices Exchange, a private exchange which offers plans to active employees of more than 2,300 companies.

Cohen said people in the future will "laugh" when they recall a time that their companies picked a single insurance plan to cover the health needs of them and thousands of their co-workers, without giving them any choice. "The last bastion of what you can't buy online is health insurance," Cohen said. "That will fall, just like everything else did."

Cohen predicted that in the next six months, "you'll see lots and lots" more companies signing up for private exchanges, including Fortune 1000 companies.

"I really think that within five years, the vast majority, I think 70 to 90 percent of companies, will be using exchanges for their active population and their retired population, and it will be the normal course of business," said Cohen.

—By CNBC's Dan Mangan. Follow him on Twitter @_DanMangan.