Here's a great thread on how AA was killing it 4 years ago and a bunch of United pilots wishing they had AA's management team and profitability...
I know AA hadn't much intergrated AA/USAir yet and UAL did in fact get a major mgmt makeover but I think it shows how quick the top dog can go to the bottom and the bottom can rise to the top. All 3 legacies are making between Billions a year at the moment. I wouldn't waste too much time worrying about any legacies going bankrupt in the immediate future.
I'm thinking there may be something to what a lot of guys are saying about the legacies will continue to leap frog one another far into the future.
How pathetic are we?