Parcel Business Is Drying Up

No such thing with planes like that. The routine maintenance and upkeep isn't optional (like with some o/o's lol) nor is it cheap.

 

Yeah flight crew, another massive expense! I knew you weren't serious, was just saying..

 

Don't forget scheduled maintenance. Those phase checks will just absolutely kill you if you don't have a quick turn-around time. Quick turn-around times needs a good shop and mechanics with the tools and knowledge to make it happen.
Also, life limited components. A lot of those airliners sitting at Mojave are just about timed out. They'll eventually be scrapped or sold to some sleaze-bag operator in South America or one of the mud hut nations in Africa.
Some of those Mojave planes are so far gone they won't be allowed back in the U.S. A lot of them have major corrosion issues and ADs due.
They'll keep flying and being patched together until they just won't fly anymore...or until they crash.