"What Congress cannot do under the Commerce Clause is mandate that individuals enter into contracts with private insurance companies for the purchase of an expensive product from the time they are born until the time they die."
-11th Circuit Court of Appeals
Should this end up going to the SCOTUS, which I believe it will, it'll be quite interesting. I suspect the Conservative members of the Court will find it unconstitutional, the liberals will find some inane, convoluted reasoning for why it's permissible, and Justice Kennedy will be the swing vote.
I can't think of anytime in U.S. history where Americans were required by law to purchase a product on the private market based on no condition other than the fact that they reside in the U.S. The natural question, should this be ruled Constitutional, is, "what other products can the government compel me, under penalty of law, to buy on the private market?"