The answer is that the states need to enforce the 10th Amendment of the constitution. Unless a product is transfered across state lines the feds have no jurisdiction. So its going to take a tough Governor to order the feds off state property and if necessary order the State Police to escort the feds off of state property.
At some point its going to take one tough governor to start the ball rolling and once started it will gather momentum. But its going to be rough on the first state that does this, but the time is right.