Of course, both Parente's and CBO's numbers are both their best guesses of what the insurance market will look like in the next 10 years. Which is to say they are very much guesses. Parente's model, developed about a decade ago, emphasizes the types of health plans people tend to choose, as opposed to what's available.
So, how does Parente's model explain the big drop-off in coverage between 2016 and 2017? He cites two major factors: the scheduled expiration of ACA programs meant to blunt major rate hikes and the phasing in of new health plan requirements as old health plans come to an end.
On the first point, the temporary reinsurance and risk corridor programs are scheduled to end in 2016. These programs are designed to stabilize premiums as insurers adjust to the health-care law's new coverage requirements, with the idea that the reformed market will settle within three years.
To the second point, Parente estimates between 4 million and 6 million people will see their existing individual coverage end in the next few years when either their plans lose grandfathered status or the White House's extension of non-compliant health plans runs out near the end of 2016. These holdovers from the individual market predating the ACA are expected to be younger, healthier and more sensitive to price.
People buying the bronze plans tend to be more sensitive to price, and Parente's model finds the premiums will outpace the value of federal subsidies to purchase coverage through Obamacare health insurance exchanges. As a signal of price sensitivity, people getting coverage through exchanges in 2014 were much more likely to pick bronze plans if they didn't have help from federal subsidies.
There are, of course, many unknowns surrounding the ACA's future, such as how many states will expand Medicaid and the employer mandate. But Parente's analysis suggests the Obama administration faces some significant implementation challenges in 2016, which is also a presidential election year.
And, of course, by 2017, a new administration will be responsible for the law's ongoing implementation.