Disclaimer: No one outside the Court knows what the Supremes are doing. Those who talk don't know, those who know don't talk. And no one can predict a case's outcome from oral arguments.
But if it's true -- as Politico suggests -- that Justice Ginsburg is authoring a dissenting health care opinion, that's great news for ObamaCare opponents. She is clearly disposed to uphold ObamaCare; her status as the most senior justice among the Court's predictably liberal bloc (i.e., herself and Justices Breyer, Sotomayor and Kagan) would guarantee she would have the prerogative to craft the dissent (and she would no doubt seek to do so in the tradition of former Justice Brennan, who wrote dissents designed to be used to support majority opinions in future cases).
Justice Sotomayor, who displayed some skepticism about the law during oral argument could win great points for intellectual independence by voting to strike down ObamaCare -- but the fallout from the liberal community would be so intense that my guess is she won't.
To my mind, the fact that Justice Kennedy authored the opinion that was largely favorable to The White House on the Arizona immigration statute is also a positive sign. Justice Kennedy cares greatly about his standing in the elite-liberal establishment, and I suspect he would go to great trouble to "balance" striking down ObamaCare with an opinion more likely to be palatable to The New York Times.