While I agree with you in part on your extrapolation regarding the large importers/manufacturers/etc., also knowing that Imperial Hobby Productions can sell trolley bodies through Shapeways
http://www.shapeways.com/shops...§ion=O+Scale
for under $200 tends to tell me that a small entrepreneur can do the cars discussed here through 3D printing. Now, whether modelers will buy them in another issue entirely having to finish them out, paint & decal, etc.
I also know that if I had the master in hand, I could probably pour resin to make a set or 3 every day (not happening....). Again, whether modelers will buy them in another issue entirely having to finish them out, paint & decal, etc.
Maybe if the demand is real enough, some enterprising person will actually do something more than expect some importer/manufacturer to answer their, "Please build me.......".