I'm kinda in Rick's camp here. I never really thought the movies were that big of a factor, cause a lot of folks never saw them. It was the folks in the general area that I think were there pushing for the survival of the Cumbres line, and the tourists on the Silverton line kept it alive.
My father went for his first trip in 1954, on a Rocky Mountain RR Club trip I believe. Three days including the Silverton Branch,and in 1956 he took the whole family. We made other trips out there in 1961, 1966,1968, and 1969, plus one or two I probably missed.
The reason railfans flocked to the area was that most all of the mainline steam operations were done by 1958-60, so the D&RGW Narrow Gauge was the last place in the US for die-hard steam fans. The Railroad ran lots of special passenger trains over the years from the 40's to 1966.
A large group(Depicted in our RGS show), took the San Juan with added coaches and the Silver Vista for 5 days of NG steam in 1947. So the word was out well before the movies came along. There has been a loyal following of NG fans and tourists who like the Colorado NG railroads for many decades. I think the Silverton line was kept more for economic development than anything else. Someone told me the John Norwood mentioned that in a good year the Silverton train made a modest $50K profit, about what the SG made in one day(this being in the 50's or 60's).
Everyone has their own point of view on this but it really doesn't matter at this point in time. Both railroads are here, and hopefully for many decades to come, thanks to a lot of factors including good people both past and present.
Greg