The Supreme court upheld the right of citizens in states without exchanges to receive subsidies from the federal exchange, a decision favorable to the Affordable Care Act. The 6 to 3 decision in King v. Burwell laid to rest the ambiguous wording of the law which stated subsidies could only be available to residents in states providing them through state-based exchanges.
The Affordable Care Act was the subject of an earlier Supreme Court hearing on June 28, 2012 when a 5 to 4 ruling upheld the ACA as constitutional. In NFIB v. Sebelius, the issue was, again, semantics, with ObamaCare being defined as a tax and not a mandate. States were given the right to opt-out of Medicaid Expansion.
As of now, there are still 36 states who have not set up exchanges.