Airlines' margins are so low, and price competition is so intense, that I'd bet it really does mostly work out that way in general. That said I doubt they're d

Airlines' margins are so low, and price competition is so intense, that I'd bet it really does mostly work out that way in general. That said I doubt they're directly making much money from people paying a la carte for assigned seats. I bet they get a lot more value out it letting them turn free seat selection as a perk to entice people to sign up for their credit card.