TSA contemplates banning guns at airports entirely
Snowflakes in Hell discusses it. The story is a bit ambiguous: it says TSA is considering "authorizing" airports to ban from everywhere, including parking lots.
Note that the request for the action comes from the Atlanta airport, which is facing lawsuits over its rule to that effect, which reportedly conflicts with Georgia's pre-emption statute. It's a good bet that the idea is that if TSA authorizes the airport to ban (and if TSA in turn has been given authority to do so by Congress, then that would override State pre-emption, under the Supremacy Clause. So essentially this is all over one airport.