Z force,
Depends on how they do their fleet planning, they might do what the goverment and corporations do with cars, get rid of them before they need the real heavy stuff done with them and just run a young fleet, costs more in terms of aircraft replacement, but you dont have the overheads associated with real heavy maintenance and the number of spare uned on young aircraft is less, need less day to day TLC
I have nothing to base this on, just some thoughts