Over at The Atlantic, Harvard Law Professor Einer Elhauge suggests that the Roberts decision opens the door for Republicans to privatize Social Security and Medicare:
The unseen long game is that sustaining Obamacare as a tax helps preserve the Republicans' ability to adopt two items on their own political wish list: the Paul Ryan plan to privatize Medicare and George W. Bush's plan to privatize Social Security.
Consider the Ryan plan. It would convert Medicare into a voucher that seniors could use toward buying medical insurance from either Medicare or private insurers. The voucher amount would equal the cost of the second-cheapest plan, so if traditional Medicare is not one of the two cheapest plans, individuals would have to buy a private plan to avoid paying extra.
In short, under the Ryan plan, Medicare would become a mandate to make contributions into a Medicare trust that you would later draw from to buy yourself medical insurance, which could be from a private insurer, and might have to be so in order to avoid paying a penalty. ...
So, if Roberts had held that Obamacare was an unconstitutional mandate that could not be sustained under the taxing power, that would have created a serious risk that some later court would say the same about the Ryan plan. The same risk would have also imperiled any revival of the Bush plan, which effectively converts Social Security into an individual mandate to invest your Social Security contributions into a private retirement plan.
True, the Ryan and revived Bush plans could have tried to avoid this risk by using the word "tax" over and over to describe our mandatory contributions to their plans. But the one thing that is crystal clear from the tax power case-law is that it relies on function, not labels, to decide what counts as a tax.
So Roberts could have held Obamacare outside the taxing power only if he held that functionally it could not be treated as a tax. ...