It is not unconstitutional according to the constitution. It may be wrong.
The Founders left these powers to the states. If the state does wrong, the people of that state have a political way to easily correct it. If the people refuse to correct it, in theory you can move to a neighbor state that is not committing that wrong.
But even here, Newt gets very fuzzy when pressed in interviews about this mandate. It actually sounds like he would be satisfied if, bottom line, people who have used healthcare but left others holding the bag for it are held accountable.
Left to be seen. The 10th cannot be used to supercede the Federal Constitution, or we would have slaveowning states now; or gun-free-states; or states where you may not freely speak.
Forcing people to buy a product or service will go a long way towards balancing state budgets, but it will make America unrecognizable.
Well, moreso than it is now.