Frankly, from the reports coming in so far, it is not sounding good for the health of the ACA.
UPDATE: More from Amy Howe of SCOTUSblog:
Other conservative Justices – Chief Justice Roberts, and Justices Scalia and Alito – also seemed skeptical of the government’s arguments, focusing on whether there is a limiting principle. They wanted the government to explain whether Congress can force individuals to buy things other than health insurance, including cars and broccoli, or whether the government can require that individuals exercise.