On the Commerce Clause, this was not Cardozo speaking for the majority or a minority of four. It was Roberts speaking solely for himself, his own flight of fancy. He was not joined in his opinion on the Commerce Clause by any other Justice. As for treating the mandate as a tax; yes it is a precedent, and a harmful one.
it also free the senate from the 60 person requirment to repeal.
it only takes 50 senators and a VP to repeal the ObamaTAX.