This is a bit of nonsense. First, the ruling hardly does anything to expand existing limitations on Congress' legislative power under the Commerce Clause. Second, Roberts gave an expansive reading of Congress' power under the Taxing Clause, susceptible to the exact same slippery slope (broccoli) arguments that were made against upholding ACA under the Commerce Clause. Third, Roberts has consistently demonstrated that he's simply not that concerned about states rights and federal power (the immigration case immediately comes to mind). If anything, he knows that's a losing battle. The Healthcare Cases are better understood as an attempt by Roberts to save the political capital of the Court for other fights -- such as affirmative action, voting rights, marriage equality, corporate speech -- and not as a sneaky way to further the federalism agenda.
I don't know enough about constitutional jurisprudence to have an informed opinion of my own. But the arguments I've seen along these lines haven't struck me as particularly convincing -- at most, setting up of a few low walls no one was going to try to get past anyway. How often was Congress going to try to regulate 'inactivity' going forward? Broccoli? But I want to hear from you TPM Readers who actually know your Commerce Clause caselaw. What do you think?