It's only unsustainable if the product is offered at an unsustainable price. It is only offered at an unsustainable price if competitors have a regulatory advantage. Competitors only have a regulatory advantage if we "open the skies". We would only ' open the skies' if we were of the belief that a pure " free enterprise" ideology was acceptable to us from a commercial/ sovereignty/ safety perspective when applied to Airlines.
In short, if everyone has to build rosters that afford well rested crews, the ticket price goes up by $3 a ticket and life rolls on.