Richard and All,
No one hates to see NMJ empty more than me. Its depressing.
However, operationally it is simply too far south. With the reduced motive power requirements of a modern railroad in this area, fewer engines due to increased horsepower and declining traffic, a centrally located engine servicing facility makes more sense than one on the tail end of the main line and the start of a 30 mile branch. Millinocket, seeing as it is the current operational hub, would make the most sense for a major repair facility, but Derby is acceptable, as it is much closer to the former CP line west of Brownville Jct than Millinocket is, making servicing of this major corridor easier. Millinocket is a fueling, sanding, minor repair facility, and frankly, units only need to go to Derby for major work, and inspections. The rotation of motive power works very well, in my opinion, without NMJ in the mix.
NMJ used to be a major rail hub, and some units rarely left there, for instance, NMJ used to have 24 hour switching, the units that switched NMJ very rarely left NMJ. It would be necessary then to have a fueling facility there for them, and if the Medford cutoff were still in use, some trains would bypass Derby altogether, and head straight for NMJ. In that scenario, NMJ would work rather well.
In light of the centralization efforts by most modern railroads, I think it is unlikely to see NMJ reactivated, but one can hope.
On a related topic, there was rumors at one point about Iron Roads moving all shop work to Millinocket, and abandoning Derby Shops. Never happened, but it does leave one to wonder.
cya, Joey