First the good news, it appears that the Covered California marketplace is working. People are selecting lower cost options and forcing insurers to compete. Gabel et al. (2017) state that
…the average purchased price for all plans was 11.6 percent less than the average offered price in 2014, 13.2 percent less in 2015, and 15.2 percent less in 2016. Premium growth measured by plans purchased was roughly 2 percentage points less than when measured by plans offered in 2014–15 and 2015–16. We observed shifts in consumer choices toward less costly plans, both between and within tiers…
More, generally patients visiting federally funded health clinics in states that had Medicaid expansions saw the quality of care they received improve. Cole et al. (2017) write that:
states’ decisions about Medicaid expansion have important consequences for health center patients, with expansion improving treatment and outcomes of chronic disease and bolstering the use of recommended preventive services.
On the other hand, many people are not getting the subsidies for which they are eligible, particularly the poor. Fung et al. (2017) find that:
…31 percent of individual-market enrollees in California who were likely eligible for financial assistance purchased plans that were not silver tier or that were not sold on the state’s exchange and thus missed opportunities to receive premium or cost-sharing assistance or both. Lower-income enrollees who chose plans not eligible for subsidies had two to three times higher odds of reporting difficulty paying premiums and out-of-pocket expenses during the year, compared to those who chose eligible plans. Regardless of how the structure of the individual market evolves in the coming years, efforts are likely needed to steer lower-income enrollees away from financially suboptimal plan choices.
Of course, all of this may be a moot point if Trump fully repeals Obamacare and its health insurance exchanges.