Mesa is an old regional. When I first was hired I flew with a lot of Captains that had been with the company 20+ years. (Doesn't happen much anymore as upgrades are running galore.)

These guys are set in their ways, mostly are above the age of 50, make more than 100k a year and have no interest in starting over at the bottom of a mainline list and sit in the right seat for the last 10-15 years of their career.

Also you have to remember pre-bankruptcy Mesa's seniority list consisted of 1800+ pilots. Once all the Dashs, 145s and 200s got parked, that list shrunk to a mere 600 pilots, leaving only the most senior guys in the left seat and most of the relatively young pilots bailed to other airlines.

Long story short, I'd say 200-300 guys on the list are lifers. Don't have a list in front of me but I think there's maybe 900 total on the list now.