Success of the exchanges, however, will depend on how many people and businesses use them. Too few enrollees could drive up premiums if those who choose to enroll are sicker or older than those who sit out.
And subsidies will be key to getting people to enroll through the exchanges, experts say. Such funding, however, is expected to be a target of the law's opponents.
"I don't think people are convinced that Romney would repeal the whole thing, but certainly huge swaths of funding could be taken out," says Young. "If you take out the subsidies, then the exchanges won't gain a toehold and may well collapse."
Premium costs will be another key factor in enrollment in the exchanges. The Congressional Budget Office has estimated that premiums for big employers will be a little lower under the law, while costs for small businesses will remain about the same. Individuals will see higher premiums, mainly because coverage will be more comprehensive. For some individuals, the CBO said the additional cost would be offset by subsidies.
A survey by consulting group Mercer released in August found that 60 percent of the 1,200 responding employers expected some cost increase from the law in 2014. Watts says those costs are mainly related to having to cover more workers - including those employed at least 30 hours a week -- or from higher employer payments toward the benefit packages.
"The law does figure out how to provide access to benefits for 30 million Americans who don't have it," says Watts. "Beyond that, there's not a whole lot in there that helps manage costs for employers. You could argue that will be a byproduct of the law, but there's no certainty around that. Time will tell."
No matter the outcome Tuesday, she and other consultants say the trend toward private insurance exchanges will continue. Employers like the concept because the private marketplaces make it easier for them to set caps on the amount they pay toward premiums, allowing employees to choose more expensive plans if they pay the difference.
If premiums rise faster than the caps set by employers, workers would pay more, picking up a growing share of costs. Proponents expect a tempering effect on premiums, however, through competition among insurers that sign up to offer coverage through the private exchanges.
A number of private exchanges, run by consulting firms and insurers, are already capitalizing on the trend, offering an alternative to the future state-based marketplaces.
Benefit consultant Aon Hewitt, for example, has a private exchange for its workers and recently signed deals with Darden Restaurants and retailer Sears, which will send tens of thousands of their workers to the exchange starting in January.
UnitedHealth Group, one of the nation's largest insurers, has purchased Connextions, a firm that helps form exchanges. The Blues plans, through Wellpoint and Blue Cross Blue Shield of Michigan, have bought into Bloom Health, which runs an employer exchange.
"On the employer side, private exchanges are the main action under either an Obama or Romney administration," says Joel Ario, a consultant at Manatt Health Solutions and former Obama administration official in charge of exchange planning.
He says state-based exchanges, like the one already operating in Massachusetts, work well for individuals, but have not caught on as fast with employers. "A lot of employers will be saying they like the exchange idea, but may not want to be in the public exchange, unless they can get a tax credit."
Kaiser Health News is an editorially independent program of the Henry J. Kaiser Family Foundation, a nonprofit, nonpartisan health policy research and communication organization not affiliated with Kaiser Permanente.