Federal exchange access was an important victory because only plans offered on the government exchanges are eligible for subsidies.
(Read more: How do Obamacare exchanges work?)
The online brokers have not succeeded in gaining access to exchanges in states that have built their own marketplaces, like California, New York and Maryland.
Lazard Capital Markets analyst Steven Halper thinks the states are being protective of the investment they made in developing the exchange infrastructure and jobs involved in operating the marketplaces.
"The upshot is the states have gotten federal grant money from the federal government to develop the exchanges themselves," Halper said, "and they're looking at it as an opportunity to put people to work and develop this capability, and they do not necessarily want participation of the private sector, at least initially."
Side-by-side price comparisons
Halper said it's not clear how many people the brokers will be able to divert from the federal exchanges, but he expects them to see some incremental growth.
The online brokers insist they're not competing with the government exchanges, but point out that they'll be able to offer consumers something the state exchanges will not: a side-by-side comparison of state exchange plans and plans being offered in the private sector.
For those who are at the top range of the income eligibility for subsidies, eHealth's Lauer said an exchange plan may not necessarily offer the best value. That's where the online brokers' call centers, staffed with people experienced with health insurance plans, could make a difference.
"It's going to be our job to help educate people in an unbiased way, so that they can—a consumer can—make a decision that makes the most sense for the individual or their family," he said.