The time has now come, where airlines are squeezing the GHAs for everything - and then some more... AND all for peanuts.
The low-cos are leading the way, with their minimal turnarounds. They can only offer 'low-ish' prices, IF they can secure even lower handling costs at their airports. They make deals with airport authorities on parking and landing fees too and get subsidies from certain local governments. The internet has greatly reduced their costs with on-line booking and checkin, as well as self checking in at some airports on automated checkin machines.
The majors are now waking up and smelling the coffee... They can contract out for a fraction of the cost to a GHA, and let them deal with the operation. BUT there is only so-far a GHA can go before they end up doing the job for nothing - at best in some cases...
The GHAs do a great job in most instances, under the circumstances... The airlines agree a fee over a fixed term, which is fine, however more and more demands creep in as time goes on, and before you know it, its running at a loss.
If airlines are feeling the pinch, beleive me, the GHAs are too, and if its good for an airline to merge, consolodate or join forces, then its good enough for the GHAs - survival of the fittest, evolution etc etc...