Correct. And people on the fence now flying Big 3 won't be able to justify it during a recession if Frontier / Spirits offers that same flight 70% cheaper.
Further more what you will see during a recesion is focussing more on hub cities (DEN-ATL) vs expanding into new markets during a good economy (LGA-SJU etc etc)
Now, Big 3 will see some increase from Netjets etc passengers who can't justify doing that anymore during a down economy, but it won't be enough to make up for the amount of "normal" people flying LCC's instead paying 300 bucks more for a coke on that same route.