Actually it's much more practical to archive film than a digital copy. While there's not really anything with properties equal to Kodachrome any more you can still expect well over a hundred years from film stock under proper storage. And even then it would still be playable, just with some of the dyes starting to fade (Kodachrome would last 150 years before suffering 20% loss in the yellow, which was the weakest dye).
Can you say that of any digital format? You need secure backups of secure backups of secure backups. Things break. Then you have to consider how the industry is evolving. Can you easily recover data from a system that's 20 years old? How about 30? Do you think you'll be able to in 20 years time?
I mean, this isn't really relevant to the home user. But interesting none the less