I don't think so. Most everything can be bought across state lines. The whole point of the union was, among other things, to have a free flowing business sector.
Correct, but that doesn't mean that states have no right to regulate insurance sales that occur within their own state.
Has anybody here ever ordered alcohol through the mail from another state?
Notwithstanding the well-documented abuse of the Commerce Clause, I'm not aware of any power of the federal government that can force any specific state to offer goods or services which are sold in a different state, and I've not heard an argument that claims otherwise.
Admittedly, I'm no expert on such details, but it seems obvious that there are regulatory barriers which have been erected by states regarding insurance; I've never heard any claim that states are exceeding their rights in doing so.
I suspect that the way this change would be accomplished would be the usual "we'll withhold federal funding if a state doesn't comply" route, which a standard means of federal coercion...