Some think so, but Equal Protection and the Commerce Clause is pretty powerful stuff. You know damn well a lawsuit will be filed under that aspect and will fly through the courts.
They are going to do extensions to buy time or they are going to provoke a Constitutional crisis when the USSC orders the subsidies to all and they in some way refuse.
There is no equal protection question. Equal protection means equal application of the law, not that a law must treat every class of person in the same manner.
All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside. No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.
That’s the Equal Protection clause. And that’s why states without exchanges will somehow have to get subsidies to their citizens, equivalent to subsidies rec’d by other US citizens in other states.