The outside portion of Stuhr is organized as a collection of "villages", of which Railroad Town is the largest.
One very small grouping is built around the company store from a sheep ranch. The 5669, which is a double-deck sheep car, is included in that grouping, so I would assume that they plan to keep it regardless of its actual age (only Railroad Town is aimed at 1900 as far as I remember).
The 5669 was the only piece of NG equipment which was actually accessible when I was there last summer (the rest was behind their "no trespassing" wall), so I can't vouch for the condition of anything else.
Last night I wrote an email to them, encouraging them post a listing of surplus equipment, and to use this site as a means of locating a "good home" for any surplus equipment. However, I have no idea as to what they will actually do, so the best plan would probably still be for interested operators (CATS, SVRY, Huckleberry, etc) to contact them directly, since the wording of their notice would imply that they would rather deal with another "museum" than with an individual.