I strongly recommend Jonathan Cohn's new article about constitutional challenges to the Affordable Care Act. Cohn lays out clearly the underlying constitutional disputes and various ways it could play out. One of the many interesting questions he raises concerns the effect of a ruling holding the Affordable Care Act unconstitutional:
But many experts argue, plausibly in my view, that simply recognizing a difference between activity and non-activity would be a bold act of revisionism, because neither the Constitution nor the judicial record currently makes that distinction. And it could have far-reaching implications. “If not buying health care is inactivity, why isn’t not buying the safety equipment for your factory that OSHA requires?” asks University of Chicago Professor Aziz Huq. “Why is it that when a shopkeeper is inactive in the sense of not opening his door to, say, African Americans, Jews, or Muslims, he can be hauled into court under the Civil Rights Act? Lawyers are pretty creative. At the very least I think we would see a lot of new arguments about established laws like OSHA and the Civil Rights Act being challenged. Sure, the Court could reject those arguments. But would it?”
It's unusual for me to be at all optimistic about the direction of the federal courts, but my guess is that a ruling holding the individual mandate unconstitutional would prove to be a relatively isolated decision, rather than a harbinger of the Supreme Court restoring a pre-New Deal conception of federal power.
I see the focus on "inactivity" as an attempt to limit the effects of an anti-Commerce Clause ruling. In part, I base this on what happened after the Supreme Court's 1995 Lopez decision. Although the law struck down in that case was of relatively trivial importance, the case attracted a great deal of attention because of the possibility that this limitation of federal commerce power would lead to a "federalist revolution." But, as the legal scholar Mark Tushnet notes, "Scholars of real revolution would be amused by the Rehnquist Court’s federalism revolution. Not a single central feature of the New Deal’s regulatory regime was overturned in that revolution, nor were central elements of the Great Society’s programs displaced." And while the personnel on the Court has changed, the two departed conservatives -- Sandra Day O'Connor and William Rehnquist -- were two of the three justices who staked out positions to Scalia and Kennedy's right in Raich.
We can't be certain that a new federalism revolution will fizzle. However, when you get down to specifics, Randy Barnett-style libertarianism (even in more moderate versions) has essentially no constituency in American politics. The last Republican presidential candidate to seriously oppose the modern regulatory state won 52 electoral college votes, and those reflected the dying gasps of Jim Crow rather than opposition to Social Security.
As books by Barry Friedman and Scot Powe have recently reminded us, the Supreme Court is generally only willing to intervene in major disputes when it has the support of strong constituencies. So while it's possible that the Supreme Court would push an anti-ACA ruling much further, this would almost certainly reflect a very different political universe than the one we live in now. Ultimately, the scope of federal power will be determined politically, not legally.