Off topic... not that I disagree but the fact that everyone expects a recession in the next two years is probably the best indicator that there won't be a recession in the next two years.

The airlines will of course be negatively impacted by a recession, but the real reason for record profitability is record high levels of industry concentration (i.e., lack of competition). For the most part, the major airlines all work together in tacit collusion (the legal kind, unfortunately) to control capacity and ensure high prices. Tacit collusion is hard with 10 major players, but pretty easy with only 3-4. There would be an adjustment period but the airlines would all shrink ASM if market demand fell to keep prices (and, therefore profitability) high. Airlines with higher fixed costs (e.g., airframe depreciation) would suffer more but I think at least the legacies have the discipline to weather the storm (which is unfortunate since it hurts consumers).