The insurance industry regarded the bill as its last chance to pass measures to bring down premiums in the individual market before plans have to make decisions on where to sell and how to price coverage next year.

The $30 billion reinsurance program that was the top priority of health insurers was dropped from the spending bill on Monday, as was funding for cost-sharing reduction payments. Bipartisan support for the two measures wasn't enough to counteract disagreement on both sides over policy demands from the Trump administration, including the auto-renewal of short-term plans and applying anti-abortion language to the cost-sharing payments.

The absence of either one means that insurers will be looking at higher premiums or at absenting themselves from the markets, since other changes to the Affordable Care Act put in place by Trump have made the market definitely more of a question mark.

"Reinsurance would have been critical for counties or states that only have one plan," John Baackes, CEO of LA Care Health Plan, is quoted saying in the report. LA Care Health Plan tripled its individual market enrollment in 2018 to 76,000 paid customers. Baackes adds, "The reinsurance fund was a safety valve. Without that, they are going to have more plans dropping out."

Of course, there's disagreement on that too. Joel Ario, managing director of Manatt Health and former director of HHS' Office of Health Insurance Exchanges, is cited in the report saying that while funding for a reinsurance program would have sent a positive signal to insurers participating in the individual market, many plans that raised premiums for 2018 to account for the loss of the cost-sharing payments are now profitable. That means they're more likely to keep selling plans.

Whether they do or not, what could throw the markets a curve is the potential proliferation of plans that evade ACA rules in 2019. According to the report, proposed rules would expand access to short-term health plans and association plans that lack many consumer protections required by the ACA. "Enrollment in noncompliant plans, along with the zeroing out of the individual mandate penalty at the end of last year, create uncertainty in what the risk pool will look like in 2019," the report says, adding that healthy people could leave the individual market in favor of those noncompliant plans—leaving compliant plans to end up covering "the sickest, costliest and most heavily subsidized consumers."

Matthew Fiedler, a fellow at the Brookings Institution, is quoted saying in the report, "You could see some insurers saying: I don't know how to price for this market. I'll come back when the dust settles."