Well none obviously. Deregulation came with promises of NO loss of employment. Of course that was later translated to no loss of jobs. HA! The devil is in the details.
The legacy carriers built the safest travel industry in the world. They literally blazed a trail and built the infrastructure used by the upstarts of today. Nobody seems to care enough to save them. Nearly every safety device, procedure and advancement has blood on it; the blood of the early pioneers. And now they are having their pensions taken away and promises broken. It is a crime.
The airline industry really should be regulated in some way to prevent upstarts from destroying the legacys. If not, the upstarts of today will be the dieing legacys of tomorrow.