Some guys got stuck at the regionals, by no choice of their own (9/11, The Great Recession, age 65). I would say this is a good example of why when you select one you want to work for, you had better pick one that has staying power, a good contract, and has consistently done well, in case that ends up being you.
It's deeper though.
Good contracts come and go depending on union leadership and the economic cycle. Is the carrier in a position to both recoup lost cash and prizes AND be competitive when re-bidding for subcontracted flying? You could give Envoy a 100% pay raise across the board but if, say, Skywest can do it at a lower cost structure and similar or better reliability, the board is going to say "Sorry Charlie".
I'm not a career counselor but there is a crap-ton of opportunity out there if you're hungry. Crap Ton > Imperial Ton.