Is Obamacare a success because of the recent announcement that 7.1 million people have signed up for health insurance coverage in connection with the law? Editors of Bloomberg Businessweek, no critic of the law, see significant hurdles still standing in the way of a successful implementation.

That’s background noise: The real challenge is to respond to at least three kinds of concerns. The first involves problems with the law itself. Many state-run exchanges are poorly run; states such as Maryland and Massachusetts need help to fix them in time for the next open enrollment period, which starts in November. The law’s programs to cushion insurers from excess risk may also need reinforcement—if not enough young people sign up for insurance—to lessen any shocks to premiums next year.

There are also challenges with the health-care system generally. These include persuading still more young people to sign up next time; getting more doctors and hospitals to coordinate care; making good on the promise to make medicine more affordable; and smoothing the transition from employer-based coverage for people who lose it.

None of this occurs in a political vacuum, of course, and this is the last and most expansive challenge. If the Affordable Care Act could be said to have a single purpose, it would be to extend health-care insurance to people who cannot afford it. That said, it has proved difficult to expand coverage to poor people in states that reject the law. Some states may well follow New Hampshire’s lead, reversing their initial opposition to the expansion of Medicaid.

But if the federal government’s current strategy of exemptions and semantic dodges proves unequal to the task of gaining Obamacare purchase in states such as Texas or North Carolina, its architects will need to look for an alternative. Spending $1.3 trillion on health-care subsidies for the middle class while leaving many poorer Americans with no options threatens the moral basis for the whole undertaking.