Healthcare’s new reality could be a return to pre-Affordable Care Act (ACA) policies and turning Medicaid into a state block grant program after Donald Trump’s upset victory in the 2016 presidential election.

Trump’s healthcare proposals weren’t as detailed or extensive as Hillary Clinton’s, according to a September analysis released by the Commonwealth Fund and the RAND Corporation. The biggest and most likely change to come with Trump’s victory, and with Republican majorities in both houses of Congress, is repealing and replacing the ACA, including the elimination of the individual mandate.

“By following free market principles and working together to create sound public policy that will broaden healthcare access, make healthcare more affordable and improve the quality of the care available to all Americans,” the Trump campaign wrote in its healthcare policy paper.

The effects of an ACA repeal could be devastating, according to the Commonwealth Fund analysis. Its study said getting rid of the ACA entirely would cause 19.7 million people to lose insurance coverage, average out-of-pocket costs on the individual market would rise to $4,700 and the budget deficit would increase by $33 billion, due to Trump’s proposal to replace the law with a tax deduction.

Beyond eliminating the individual mandate, Trump’s proposal doesn’t spell out the fate of other ACA provisions, such as banning insurers from denying coverage based on preexisting conditions or allowing young people to remain covered by their parents’ plans until they reach the age of 26.

Another conundrum Trump’s win brings is what happens to Medicaid. He’s proposed turning it into a state block grant program, which could put extra strain on state and federal budgets depending on how such a change is implemented.

“We assume that states would eliminate eligibility for the ACA’s Medicaid expansion population if offered block grants based on pre-ACA funding levels,” wrote RAND Corporation health economist Christine Eibner and project associate Evan Saltzman in analyzing Trump’s healthcare platform. “But more than half of those who newly enrolled in Medicaid in 2014 were eligible under previous rules. Unless the block grants covered this woodwork population, states would have to find alternative means to finance this group or would need to reduce enrollment to break even.”

Despite all the uncertainty, professional groups have begun reaching out to the president-elect. American Academy of Family Physicians President John Meigs Jr., MD, wrote to Trump congratulating him on his victory while emphasizing implementation of the Medicare Access and CHIP Reauthorization Act (MACRA), reducing administrative burden on physicians and improving access to expensive pharmaceuticals as policy priorities.

“They will ensure continued progress toward healthcare for all, supported by a payment system that rewards value over volume of services, that promotes prevention and wellness, that protects patients from financial barriers to needed services, and that builds a primary care physician workforce that can meet the growing demand for care,” Meigs wrote. “Family physicians need your administration to make these a priority as we reform and improve America’s health care system.”

None of the proposals mentioned by Meigs were part of Trump’s healthcare platform.

In the short term, the ACA repeal will be the president-elect's top healthcare priority, as he called for Congress to hold a “special session” to scrap the law in the final days of the campaign. What he and congressional Republicans will need is a fully-fleshed out replacement plan—the last version released by House Republicans didn’t come in the form of legislation, but was instead a 37-page white paper that didn’t include cost estimates.