The point isn't so much to criticize Ektachrome of 1960, but more to illustrate how good Kodachrome is. The chance to see a side by side comparison of the same subject is kind of rare.
Certainly this says nothing at all about the longevity of Ektachrome that one can buy today. As Pupfish points out, Kodak, and Fuji are quite serious about the longevity of the materials they make and, have the benefit of 60+ years of learning. The oldest Ektachrome slides I shot are from the late 60's and 70's, and the last time I looked through them they were clearly degrading, though they still retain most of their original look. My Ektachrome shot from the 80's on look good. Aside from not using PVC my storage is far from archival.
As for Mike's question, "Buck island trip" is penciled on some of the mounts, according to Google maps, it's in Bermuda.
And yes, if I could shoot some Kodachrome in 120, I'd consider my life complete.
These were purchased in a metal slide cabinet, and the slides themselves are in Yankee plastic projector trays, probably made from Bakelite, but I've not looked at the trays closely. Other than that, I think it's safe to assume that the storage conditions were anything but archival.
I'll post more examples, if people are interested.