If you have already got high passenger volumes booked but at low yields, the impact of cancelling mid-season makes the change not worthwhile as the cost of re-protecting those customers over other routes is high. You also can't switch capacity at such short notice to another route, as you don't have the sales lead time for that to take effect. So therefore, you tough it out until you have the opportunity to exit, perhaps when an initial support package of funding to support a new route either expires completely or becomes less attractive. It's not quite as immediate a process as you seem to suggest when you're in mid-season. For a short term period, you've made your bed and have to lay in it.