I spoke to this issue in depth in a July 22 post when the issue about ACA tax subsidies was just heating up with circuit and district court rulings. The Supreme Court has agreed to hear the case. That earlier posting is still accurate. https://blogs.ksre.ksu.edu/issuesinhealthreform/aca-tax-credits-may-be-taken-away-by-courts/
The fact that the SCOTUS has chosen to take this up, and some say a bit out of expected cycle, has raised concern among the supporters of ACA, and of the tax subsidies in particular. The ACA covers many things beyond assuring affordable health insurance for many (the otherwise eligible Medicaid population in many states including Kansas got left out by a June 2012 SCOTUS decision that said the feds could not coerce states into expanding Medicaid by threatening to pull all Medicaid funds if that state did not participate). It has funds for health care workforce development and community health projects, and ways to improve the efficiency of Medicare and delivery of care in general. However, expanding the number of insured is clearly a main centerpiece of the legislation and a contrary ruling many say would effectively dismantle that aspect of the ACA. The SCOTUS will decide if the consumers in the 27 states with federally facilitated exchanges (marketplaces) can still receive those tax subsidies. Without them we would assume that insurance policies would once again be unaffordable for most as 80% of those enrolled in health insurance plans through those marketplaces nationwide are now receiving subsidies.