The margin history over the last 30 years shows a broad cycle - including long periods where the industry has actually taken on quite a LOT of pain on behalf of consumers (not that joe public cares; if prices are the same there is no competition and if prices are different there its confusing and anti-competitive). Historically, margins creep up to super-profit levels; followed by new entrants; followed by "slash and burn", where only the most efficient make any $; followed by margin increases again. Trick is to maintain a best-in-class cost structure through all of the cycles, while giving a great customer experience at all times.