You write as if Roberts had an either / or choice between obamacare and beating back the commerce clause, i.e., he could NOT do both. Simply, I ask, why not. If you earnestly believe that he has effectively "killed" the commerce clause, I would restrain you haste. Wait till the next pseudo intellectual dance on the head of a pin, with the commerce clause front and center.
On the other hand, Roberts has kicked wide open the door on the wildest schemes for taxing left only to the imaginations of the socialists. And they do not even have to call it a tax. The court will do it for them. More a fox in the hen house, I suspect.