wtpurser: the severance for many of those over 50 and crystallisation would cost too much in reality, however some would be willing to retire slightly early if a decent package came out. Unfortunately the -400 fleet has many ex-Hamble SPONSORED cadets who have flown for up to 35 years, which is the reason why 6-figure salaries can be made due to being on the top pay-point and having the seniority to bid for the routes with the most lucrative expenses.
It would admittedly be a lot more beneficial for the guys at the bottom of the ladder to keep them and lose the top guys and gals, but seniority does not work like that. The part-time work and unpaid leave options are designed to help keep those at the bottom while reducing the 'head count' and not actually firing anyone, but just waiting for the Hamble bulge people to retire: cheaper in the long run than any severance.