Alito indicated that the Court might stay its ruling in King v. Burwell through the 2015 tax year. In that case, Congress would still need to decide what to do about the 2016 tax year. In the spring of 2015, insurance companies will have to start filing their proposed premiums for 2016 with the various state insurance commissioners. They won’t be able to accurately price these products without knowing the role of subsidies in 2016.
Hence, if Alito’s idea prevails, the short-term disruption would be mitigated, but the mid-term disruption could still be a possibility.