As a long time observer of the United States Supreme Court, I am going to go out on an early limb here and make a prediction. First, it needs to be mentioned that there are so many controversies and subplots involved here. For example, there is the controversy over whether Elena Kagan should recuse herself from this case. Quite frankly, it is hard to believe that the person who was Solicitor General during formulation of this "law" was not asked her opinion- either formally or informally- by Administration officials. As far back as 1994, when Hillarycare was first proposed, the CBO and Congressional Research Service had raised questions about the constitutionality of the individual mandate. In fact, the CRS pretty much asserted that Congress would be on shaky constitutional grond. The Constitution has not changed from 1994 to 2009 so one would assume that which led them to their conclusions in 1994 still held true in 2009. And who better to answer that question than your Solicitor General, especially knowing full well that the law would be challenged in court at some point. Should she recuse herself from the case, it is quite conceivable that the final decision would be 4-4, thus allowing the decision of the 11th Circuit stand- that which struck down the individual mandate. Knowing there are no real rules regarding recusal (its up to the individual Justices), one can see where the "fight" occurs over this subplot.
There is another, more subtle subplot involved and that involves Justice Scalia. I have read several analysis of a decision he authored a couple years ago involving the growth and use of marijuana for personal medicinal use. In that decision, he ruled that Federal law trumped state law (in this case, California) and the reason was that the Federal law was justified under the Commerce Clause. Hence, the argument is that if the Federal government can disallow such a personal thing as growing and using marijuana for their own use and this is justified under the Commerce Clause, then the individual mandate is likewise justified. It is very much like the New Deal decision that a farmer who grows wheat for his own personal use (that is, the wheat never enters commerce) regardless has an effect on commerce because his witholding that wheat from market affects prices of wheat. Therefore, without the insurance mandate, a person's refusal to purchase health insurance affects commerce. That, basically, is the government's argument.
There is also the "political doctrine" subplot. This basically goes back to the early days of our Republic and the Marbury vs. Madison decision. Essentially, the Supreme Court has traditionally held the view that they cannot intervene in purely political decisions. In that case, the fight over health care can be viewed as a political fight that was resolved by the "people" through their elected officials. Quite frankly, the Roberts Court has steered clear of the political questions and they may very well view these cases as a political decision and leave it at that. Personally, I don't think they will use this as justification for avoiding the question at hand.
Then, there is the subplot of "revenge," for lack of a better word. In modern jurisprudence, it is extremely rare for a sitting President to openly take on the Supreme Court over a particular decision. They may disagree with the decision and may state that fact, but Presidents rarely, if ever, use the State of the Union address, with Supreme Court Justices sitting in the first row as a captive audience, chide that Court as Obama did when Citizens United was decided. Not only did Obama mischaracterize that decision (some Constitutional scholar, eh?), but he did so to their faces. One should never forget the look on their faces during that part of the speech that night and especially Alito's response. Yet, as Justices, they are expected to sit there stone-faced while being dressed down while Democratic Senators and Representatives hoot and holler in the background. Talk about sound-bagging someone. Could this decision be the big payback?
There is also the subplot of the concept of federalism. Perhaps no Justice more than Kennedy is big on this concept as he. Basically a protege of Rehnquist in this area, there is no doubt that Kennedy would view the individual mandate as too broad a reading of Congressional power under the Commerce Clause. And Kennedy is the swing vote on the Court- the go-to person when a vote is needed on either side. Conservatives may very well disagree with Kennedy on certain issues (for example, he relies to heavily upon tenets of international law and international "norms), but two things are important: he is the proverbial swing vote (a role he relishes since O'Connor resigned) and he is huge on federalism.
Let us, for the sake of argument, assume Kagan does the right thing and recuses herself. The vote would most likely come down to 4-4 with Roberts, Alito, Thomas and Kennedy voting to strike down the mandate. It seems strange that I would include Scalia on the other side, but if he joined Roberts, then he would have to basically rescind his reasoning in that case from a couple of years ago. That would allow the decision of the 11th Circuit stand and the individual mandate would be ruled unconstitutional.
However, lets look at the more realistic situation- one where Kagan does not recuse herself. In that instance, the vote would be 5-4 reversing the 11th Circuit- and a loss for conservatives. Roberts could try to persuade Scalia to jump ship, but the man is, if nothing else, principled. Just recently, in a case involving GPS tracking devices and wiretapping, he stated that although he originally felt the Court's decision in the wiretap case was decided wrongly, "its been around so long and we are not going to change that."
Most interesting was a little noticed act recently directed by Roberts. He ordered a Washington law firm to file an amicus brief with the Court regarding the application of the Anti-Injunction Act. This law dates back to 1867 and exists in various guises today. It basically says that no one can sue the government (any government- local, state, or Federal) over the imposition or assessment of a tax. In this case, since the mandate does not take effect until 2014 and no one will experience a "penalty" under Obamacare until 2015 (when they do their 2014 taxes), these lawsuits are barred under the Anti-Injunction Act since, essentially, no one has been harmed. Roberts did not have to order this amicus brief as it was not really an issue. When the first suits were filed in various District Courts, the Obama Administration originally challenged the suits under the AIA. When Courts began dismissing their arguments, they then dropped the issue at the appellate level. In fact, it was not that much of an issue until Roberts resurrected the subject with his amicus direction.
If the Roberts Court wanted to avoid the issue, it can simply revisit the subject and rule under the AIA that the case is not judiciable until 2015 when the first "victim" suffers "harm" via a tax penalty under the law. From a personal standpoint, this directive raised eyebrows when I first heard about it. Secondly, at times, Roberts has a propensity for deciding cases on extremely narrow grounds, sometimes minute, technical details. He is certainly extra careful to nuance decisions and tailor them to the controversy at hand. He shies from overly broad decisions and he certainly does not create new rights if they cannot be found in the Constitution or Court jurisprudence.
The conclusion is I would not be surprised if failing to reach a solid majority (and in this case, a "solid majority" would be 5-4)- that is, not some plurality decision- that the Court will simply invoke the AIA and punt the ball ahead a few years to 2015. Although it would be the wimpy thing to do, it would not be totally out of character for the Roberts Court. Even in the allegedly controversial Citizens United case, there were nuances and loopholes that allowed Congress broad leeway in disclosure and transparency requirements when it comes to campaign finance. If conservatives are looking at a knock out punch from the Supreme Court regarding Obamacare, I really don't think that will happen. In that case, Obama comes out the victor as his signature piece of legislation lives another day to fight the epic battle later on. That is why it is vitally important that Obama be defeated in 2012. With the GOP poised to win control of the Senate and retain the House- assuming they could break a Democratic filibuster in the Senate- and vote to repeal Obamacare, there is no way Obama would sign that legislation and there is no way the veto could be over-ridden (there will not be a Republican supermajority in the Senate).