Obamacare has won. And that's why Secretary of Health and Human Services Kathleen Sebelius can resign.

Calls for Sebelius's resignation were almost constant after Obamacare's catastrophic launch. The problem wasn't just that Sebelius had presided over the construction of a fantastically expensive web site that flatly didn't work. It was that she didn't know healthcare.gov was going to instantly, systemically fail. And so the White House didn't know that healthcare.gov was going to instantly, systemically fail. The demands that Sebelius to step down — or be fired — were as deafening inside the building as outside of it.

But President Obama refused. As National Journal's Major Garrett reported, Obama believes that "scaring people with a ceremonial firing deepens fear, turns allies against one another, makes them risk-averse, and saps productivity." Moreover, there was too much to be done to fire one of the few people who knew how to finish the job. Sebelius would stay. The White House wouldn't panic in ways that made it harder to save the law.

The evidence has piled up in recent weeks that the strategy worked. Obamacare's first year, despite a truly horrific start, was a success. More than 7 million people look to have signed up for health insurance through the exchanges. Millions more have signed up through Medicaid. And millions beyond that have signed up for insurance through their employers.

Healthcare.gov isn't perfect, but it works. We don't yet know how many young people signed up in March, but it's clear that there are enough of them to keep premiums stable in 2015. It's clear that insurers are going to stick with the program in 2015, and compete hard to sign up next year's wave of young, healthy applicants.

Even Republicans committed to the law's repeal are admitting that the law is back on its expected track. "The rollout made Obamacare's collapse seem like a possibility," wrote Ramesh Ponnuru at Bloomberg View. But "now that it's resolved, the debate continues basically along the same lines that everyone expected a year ago. The law will continue to be implemented, with the administration making whatever revisions it thinks necessary."

The White House says Sebelius notified the President in March that "she felt confident in the trajectory for enrollment and implementation," and that once open enrollment ended, "it would be the right time to transition the Department to new leadership."

In other words, the law has won its survival. The Obama administration can exhale. Personnel changes can be made. A new team — led by Office of Management and Budget Director Sylvia Matthews Burwell, who the White House calls a proven manager— can be brought in to continue to improve the law. And Sebelius can leave with her head held high. She can leave with the law she helped build looking, shockingly, like a success.