President Barack Obama and Vice President Joe Biden celebrated the enrollment news in a Rose Garden ceremony Tuesday. (AP Photo/Carolyn Kaster)

Today’s White House announcement that 7.1 million people signed up through Obamacare health insurance marketplaces was a great political moment for the Obama administration. Despite all the early problems with and some state enrollment websites, the administration could now say it hit the Congressional Budget Office's original enrollment estimates.

But it doesn’t really matter much for the future success of the law.

Don’t take just take it from me, though. Here’s White House Press Secretary Jay Carney, back on Jan. 6, explaining why the topline number doesn’t mean all that much for whether the Affordable Care Act will work.

Well, I think success looks like having many millions of people sign up. What is important -- because I think the conflation here is an estimate, one of which, by CBO, was 7 million, of a total number of enrollees and what that means. Obviously, the more enrollees there are, that’s a measure of success. But in terms of how effective the marketplaces function, the makeup, the mix of the population that enrolls is more important than the total number. And that’s why so many efforts are underway to reach different populations with the message of the options available to people for quality, affordable health insurance.

Yes, getting more people enrolled in coverage is the whole purpose of the Affordable Care Act. It wasn’t going to happen all at once, though – chipping away at the uninsured rate was always expected to take years.

So, whether that was 5 million or 6 million or 7 million in the first year, that didn’t entirely matter for the law's survival. As Carney says in that press briefing, the future success of the law will depend on the mix of enrollees – have enough healthy people signed up to help offset the costs of sicker patients?

Further, it’s going to depend on the mix of enrollees in each specific state, since there are 51 unique insurance markets (including the District of Columbia) that are now all living under this system. You’re going to see some states that thrive under the ACA and others that will surely struggle, depending on a number of factors, like demographics, political attitudes toward the law and the history of their insurance markets before the law.

There’s much we need to learn about this first enrollment period, which is still going on for people who struggled to enroll before March 31. Of course, we still need to learn how many paid their premiums to complete enrollment. Health and Human Services Secretary Kathleen Sebelius on Monday said it’s anywhere between 80 and 90 percent, so official enrollment (and not just signups) could be anywhere between 5.7 million to 6.4 million. Those numbers would still likely rise over the next few months for those who can sign up later because of hardships or changes in life circumstances.

Other things we don’t know yet: How many of the previously uninsured signed up for private plans or Medicaid? How many people skipped the exchanges and signed up directly with insurers? How well did insurers predict their mix of enrollees in 2014? Will people actually like the coverage they now have?

Finding all this out will require some patience, which is pretty hard when this law is under constant attack and the administration tightly controls the information that it releases. If it’s any solace, it’s going to take two or three years, anyway, to truly get a handle on how this law is performing.