Regardless of one's views on the Affordable Care Act, the Supreme Court’s majority decision appears to be the correct reading of Congress’ intent when adopting the law. The following excerpts of the Court’s decision are particularly relevant:
And by using the words “such Exchange,” the Act indicates that State and Federal Exchanges should be the same. But State and Federal Exchanges would differ in a fundamental way if tax credits were available only on State Exchanges—one type of Exchange would help make insurance more affordable by providing billions of dollars to the States’ citizens; the other type of Exchange would not.
Had Congress intended any other approach, the legislation would in effect have been largely self-defeating. In other words, the Congress would have created a massive escape clause by which the status quo could be preserved, even as Congress intended to change the status quo.
It’s difficult to imagine that Congress would have expended all its effort on a highly-contentious matter to then allow others to easily render its efforts irrelevant. At worse, one would be dealing with a technical error, not the intent of Congress. Essentially only political cynics who believe the government has become near-totally dysfunctional could believe that Congress would have deliberately taken on a difficult issue, readily assumed the costs of doing so, all the while intending to make its law structurally irrelevant.
Put another way, does Congress intend to pass laws merely for the sake of illusion but no desire that they take effect? That's what a contrary decision would have required. It is no surprise that a 6-3 majority chose to uphold the law.
This does not mean that the Supreme Court endorsed the merits of the law, much less the impact of an adverse ruling's outcome. Instead, assuming Congress is rational, it concluded that Congress' original intent was that states could take the lead on creating exchanges, but in the absence of such leadership, the federal government could create such exchanges. All exchanges would enjoy the same tax treatment.
Of course, I will note that I could be wrong. But that's how I see it.