Seven million people signed up, so there is an appetite for President Obama's health care law, but that doesn't guarantee success for the country's newest social program.
Big challenges are lurking for the next enrollment season, which starts Nov. 15. Chief among them are keeping premiums and other consumer costs in check, and overhauling an enrollment process that was advertised as customer-friendly but turned out to be an ordeal.
"They have demonstrated the law can work, but we are a ways off from being able to judge its success," said Larry Levitt, an expert on health insurance markets at the nonpartisan Kaiser Family Foundation.
Republican opponents of the law keep pushing for a repeal, but as millions of people obtain insurance, how long can the party's strategy remain a politically viable option?
"What the Republicans need to really pay attention to is what they would do different from the Affordable Care Act," said economist Gail Wilensky, who ran Medicare under President George H.W. Bush.
"Just talking about repeal is not going to make it with 7 million people getting insurance on the exchange. And it has to be something reasonably credible ... it can't just be repeal. We are beyond that."
The source of the pent-up demand that propelled health care sign-ups beyond expectations could stem from the nation's new economic reality: a shrinking middle class and many working people treading water in low-paying jobs.
Health insurance has been one of the pillars of middle-class security for decades. With fewer jobs these days that provide health benefits, there was an opening for a government program to subsidize private insurance.
When Medicare and Medicaid were created in the 1960s, policymakers took it for granted that people working steady jobs would have access to health care, said Len Nichols, director of the health policy center at George Mason University in Virginia.
That was "back in the day," Nichols said. "Our assumptions have been all along that you could buy what you needed. But you cannot. And that is why we are where we are."
It could take the rest of the year to sort out how many uninsured people have actually gotten coverage, the ultimate test of Obama's law.
Early statistics provided by the administration have not been useful, mingling uninsured people with those who previously had coverage.
But an ongoing Gallup survey has shown a steady drop in the share of Americans without insurance since Jan. 1, when the law's main coverage expansion took effect. Those numbers should improve because many people still can take advantage of extensions granted by the administration, and because those eligible for the law's Medicaid expansion can apply at any time.
Still, vindication for Obama's law isn't guaranteed. Among the top challenges:
Health insurance premiums tend to go up every year, so the question now is how much higher in 2015.
"How fast they go up will no doubt vary across the country," Levitt said. "Public judgment of the law will be influenced by how rapidly premiums rise."
There's a back-and-forth going on, he said. An improving economy and the law's taxes on insurers will tend to push up premiums. Mechanisms in the law to assist insurers with a disproportionately large share of high-cost patients will push down premiums.
The big unknown is what economic bets insurers made when they jumped into the markets created by the law. If they were conservative and figured a big share of costly cases among the newly insured, that would take some pressure off premiums for next year.
Another important affordability issue has to with deductibles and copayments that consumers have to pay when they use their insurance benefits. Many of the new plans have high out-of-pocket costs, a trade-off for keeping premiums low.
The advocacy group Families USA, which has supported the law from its inception, says the government should nudge insurers to cover more routine medical care outside of the annual plan deductible, the amount consumers pay before insurance kicks in. Right now it's mainly preventive services that are covered outside of the deductible.
OVERHAULING THE SIGN-UP PROCESS
One of the law's main goals was to take the mystery out of purchasing insurance, in the same way buying a car is less intimidating these days because prices, quality ratings and loan rates are easily available on the Internet.
But even when the websites are working, the insurance exchanges are anything but easy to navigate.
Finding out what hospitals and doctors are in particular plans requires additional work. Also, experts say it's really difficult to get to a true bottom-line estimate that includes premiums and expected cost-sharing.
"The promise has not been realized," said Robert Krughoff, president of Consumers' Checkbook, a rating service that evaluates health plans for members of Congress and federal employees. "The law says the exchanges will assist consumers in making easy plan choices, and that has not been realized. But it could be."
One common recommendation is to provide consumers with much more in-person assistance to enroll and pick a plan. A change that might help meet that goal is to align sign-up season with tax filing because that could enlist the help of tax preparers.
As it stands now, the administration has scheduled open enrollment season to end on Feb. 15, 2015, right around when most people are just starting to think about filing their taxes.
Krughoff says better online tools are needed to estimate costs and find hospitals and doctors.
"I do think there are many cases where consumers will have joined plans that will cost them a lot more than they could have," he said.