"Stuck" with an airline? Have you missed the large recruitment campaigns by Etihad, Emirates, Easyjet, Ryanair, Qatar Airways Air India, SIA and BA? Pilots are highly employable elsewhere but in most cases the cost of changing employer means its not worthwhile. That, for the benefit of 20driver, is why being average on the annual evaluation gets you a guaranteed pay rise every year, because if that didn't happen those highly employable staff would be changing employer every other year.
As for the actual job never changing, well it certainly changed when I went from flying high frequency short haul flights in Europe to long haul flights worldwide in a different aircraft type. When I get bored with that I'll probably go for a command ona different aircraft type with another change. Perhaps going into training could be an option. Or, God forbid, management. Plenty of variety here, unlike say medicine or law where all you do is spend your career doing boring old medicine or law.
