Would the Supreme Court Dare Undo the Mandate?

In the course of an interesting musing about the constitutionality of the mandate, Ezra Klein makes what seems to me to be a slightly odd prediction:

Now the individual mandate is traveling through the courts. A judge appointed by Bill Clinton has ruled it constitutional. A judge appointed by Ronald Reagan has signaled that he might do the opposite. Last week, Bill Dailey asked whether I truly believed the Supreme Court part of this cynical dance. And the answer is yes, I do.

That doesn't mean I think the Supreme Court will rule the mandate unconstitutional. Coming on the heels of Citizens United, that would spark a tremendous confrontation between the Democratic Party, the Democratic president, and the Supreme Court of the United States. There are good reasons for them to prefer avoiding that outcome. They may try to split the difference, offering a limited ruling requiring slight tweaks to the mandate.

But the evidence on past Supreme Court decisions, the heavily political process through which Supreme Court justices are now chosen, and our intuition -- the Supreme Court is full of human beings, and human beings have biases -- should make us very skeptical of claims that the Supreme Court is somehow removed from politics, or that the same partisan forces that turned the individual mandate from a conservative idea into a conservative bete noire are not behind the arguments now playing out in the courts.

To put it slightly differently, I have no concerns about the abstract constitutionality of the individual mandate. Insofar as I have any concerns, they're about the partisan leanings of the Supreme Court's current occupants.

I assume that the Supreme Court will be extremely reluctant to strike down the individual mandate, for a whole host of reasons.  But I do not think that political worries will be among them, because the mandate is extremely unpopular.  Nor do I believe that the Supreme Court justices will be checked by the fear of "a tremendous confrontation between the Democratic Party, the Democratic president, and the Supreme Court of the United States."  Ezra seems to be envisioning something along the lines of FDR's court-packing showdown, which culminated in "the switch in time". This seems unlikely in the extreme, for several reasons:

1. FDR's court-packing scheme failed, blocked by his own party.  At the time, one might kinda-sorta plausibly argue that the size of the court had been changed before, and could legitimately be again.  But the failure of the court-packing scheme has basically enshrined the nine-member court in public sentiment.  Obama has no power to take on the court; all he can do is replace liberal justices who retire with other liberal justices.  He may get lucky if a conservative dies on him, but otherwise, he's pretty limited.
2. Beyond that, Democrats are almost certainly going to lose the House, and they may lose the Senate; at best they will only have a very thin Senate majority.  This is not enough political power to start a "confrontation" with the Supreme Court, especially since
3. FDR was working with a legislative system that allowed much more centralized control; he essentially needed to get the support of a few powerful figures in each chamber.  Moreover,
4. The mandate was the most unpopular part of an unpopular bill.  If Obama and the Democrats went to war over this, the confrontation would be extremely politically costly for them, not for the Supreme Court.
5. By the time this actually gets to the Supreme Court, the Democrats may not hold the presidency, either.

The Supreme Court is worried about the legitimacy of its own institution, but I see no evidence that a ruling invalidating the mandate would jeopardize that legitimacy.  Yes, it would piss off a lot of Democrats, but I doubt the majority of the court really cares all that much.