All that remain in service. Some fraction will remain certified that could receive ADS-B if another hull had to be abandoned (say a ground truck incident where the ADS-B could be moved).
I do not know ferry permit rules. There isn't much of a second hand market. Not since used A319s went at scrap rates. Then again, used prices might receive a boost.
Thanks. My thinking about second-hand placements is about non-US markets, used to fix MD-80's with presumably very few resources. Venezuela and Iran come to mind. Also Bulgaria has a dozen or so of MD-80's flying. With old equipment and cannibalization, it's often very useful to have plenty of spares at your disposal nearby, than already harvested components in third-party warehouse, on the other side of the planet (talking with personal experience, though in non-airplane environment).
Also, Everts Air Cargo is poised to be in MD-80 game for some time. Would it make sense for them to add a few MD-80 frames more, as their DC-6 fleet is not getting any younger?
The problem with the MD-80 is the spare market for critical parts is rapidly drying up, especially as AA stretched their fleet a bit longer than initially planned. Used A32Xs and 737NGs just make more sense. Many are getting cheap, parts are plentiful, and it is only a generation behind current tech and not two.
I 100% agree on spare parts being an issue. In no way do I expect much of a life extension. As I posted before in this thread, the utilization of green time engines to keep the MD-80s flying caps how much they can fly. To my knowledge, DL stopped engine overhaul last year. To my knowledge, that is because the few engine parts left are being used to do minor repairs to otherwise good engines.
But if an MD-80 were knocked out of service, there are a few non ADS-B MD-80 that could receive the avionics (and probably engines) to nurse the fleet through the limited remaining life.
DL has options for new aircraft (including newer used aircraft).
The limited MD-88+MD-90 fleet is facinating.
The fleet will limp along longer than I thought. Then again, I didn't see any MD-88 upgraded to ADS-B. I also thought the MD-90 would be around longer. DL spread out overhauls between 3 shops with a tiny fleet, so 2 called it quits and the 3rd was the most expensive option ending operational viability. I estimate this increased MD-90 operating costs about 5% on just engine overhaul.
Winter is coming.