I toured the Micro Trains Factory in Talent, Oregon during the summer and in their development room there were blown up plans of the reefer and the boxcar on the wall. However, when I asked the owner of the company about their plans for a boxcar I was told the same thing, that there were no current plans to expand the line. You never know with Micro Trains. If enough interest is expressed in a particular item they might proceed. The real cost is in the development and they have to be able to get their investment back to make it worth it.
Daniel