If the Roberts Court decides to throw out the mandate and universal coverage, that will be a significant and painful moment in the fight to make all Americans covered by health insurance. It will also represent a further rightward shift in our understanding of the role of government, a further undermining of the past 65 years of American jurisprudence. It would be a return to Gilded Age distortions of the law.
But if the Roberts Court decides to throw out the entire ACA or toss over the Medicaid rules... We are talking about a moment of judicial activism that can probably only be compared to Dred Scott V. Sanford in terms of its far reaching implications and what it means for the Court's legitimacy.
If Citizen's United dramatically and radically re-wrote a century worth of campaign finance law, then the overturning of all of ACA and the prohibiting of federal pressure on the states through the purse string would shatter almost all precedents since 1937. This would profoundly rewrite the very function of the American governmental system.
Which is why it's unlikely Kennedy goes along with it. Roberts, too, might decide that being the Roger Tawney of the 21st century isn't the legacy he had planned for himself.
The mandate might very well be overturned and with it the universality of ACA. But I think the Court might blanche at completely overturning 65 years of precedent.
Of course, the question becomes did they learn from Bush v. Gore and Citizen's United? Or are they just getting warmed up?