The 6 (framed) tank cars that came back from Alaska arrived in Alamosa on flatcars. That was in the early 90's.
I'd suggest the pain from no standard gauge railroad service in the Valley would be indirect; with no shipments out of Antonito of Perlite or lava rock, there would be even more economic distress in the area. More trucks on the road over La Veta Pass hauling potatoes and other agriculture products.
The cars being stored on the SLRG are fairly new and baring any sudden increase in the need for coal or oil shipments elsewhere in the country, will be there for a long time. The line to South Fork has probably never been so profitable!
Bill Kepner