As 2017 ended, Medicaid's entitlement structure—and the funding base on which this structure rests—remained intact. During the Trump administration's first year, this largest and most unique form of US health insurance faced an existential threat under three distinct waves of legislative attack as part of the efforts to repeal the Affordable Care Act (ACA). The first two waves would have preserved the ACA's transformative change by maintaining the eligibility category created by health reform for working-age low-income adults. But the price exacted for this concession was enormous: loss of the very federal funding on which the ability to provide coverage rests. The third wave would have gone further, not only destroying Medicaid's open-ended funding structure but also stripping states of the option to extend federally-financed assistance to all poor working-age adults. The effort to effectively end Medicaid as we know it failed for both political and policy reasons, but the existential threat continues in Congress, the executive branch, and the courts.