Any airplane is economical at any fuel price. The difference is if the tickets can support it. If this new merger allows for some price control then the ticket price will go up to reflect the cost of operating the flight. The past decade has shown that even with 777s flying around with relatively cheap fuel you can't make money with no price control. So at what point do we just stop flying all together? I seriously doubt people will stop flying even when tickets cost $1000 to go from LA-NY. They did it in the 1950s, they can do it today.