The lost decade was worse, at least based on what we know right now. COVID is a single discrete event, and while it's deeper and uglier at face value it has a likely discrete end-point (vaccine). We will also not be fighting trillion-dollar wars over covid for the next 20 years (hopefully).
The lost decade was a combination 9/11, SARS, 2008 downturn + sky-high oil prices, and to top it all off age 65. Also what a lot of people don't realize is that on 9/11/2001 the industry still carried a lot of pre-deregulation fat... that all got trimmed during the lost decade.
If it hadn't been for age 65 it would have been the lost half-decade. It's unlikely they'll raise the age again, especially now, and even if they do it would only be 67 (there's international precedent for that).
Baring any other black-swans, and still considering (now accelerated) retirements I suspect things will be back on track sooner than many folks might think. Five years of little or no hiring is a pretty typical of industry cycles, even though it may be a big wakeup call for the younger crowd (Congrats, you've had your cherry popped by the industry
)
Even if the big three are down longer-term, there will still be some opportunity in cargo and LCC, and those are still good livings by most standards. Also this is going to scare off a bunch of new entrants, so there will be opportunity for those who stick it out (I've seen that movie before too).