Your whole list helps point out the problem. Mesa Verde, Aztec, The whole 4-corners area, including Lakes Powell, and Navajo, Ski areas like Purgatory, already have their own narrow gauge railroad (Durango & Silverton). Add the existance of a college in Durango. These are among the things that attract people to that vicinity.
Over in the center of the state, I'm sure Taos sends some business over, but Taos is trying to attract tourists to itself. And has plenty to keep them busy, what with river rafting, the ski area, art galleries & all. Now, if you could plunk Taos down at the end of a railroad, then you'd have something.
Bandolier is another one. While it is a great place to visit, it is rather primative with regard to accomodations. And being over two hours away from Chama, they probably don't associate well.
Now if Ghost Ranch was more of an attraction, Or if resorts were built on some of the northern N.M. lakes.
Of course, the next thing you know, you'd have a McDonalds next to Chama Depot, and you'd have to put in a second stop light. Or next to Antonito depot and you'd have to put in a stoplight.