I agree that the best move is always to back up the material on a stable ANALOG storage medium. But that's difficult or impossible for the *average Joe* with a collection of digital photos, not many "film printers" around that you could use. So continual migration (and/or donation/sale to a place that does that as part of curation) is vital for modern materials.

I also do some audio restoration work. It's interesting that the preferred archival medium for sound is still a well-produced and carefully-stored analog magnetic tape. It'll still be playable in 50 years; unless actively managed, the digital files will be long-dead by then. The LP records cut from those (if done) are still fine, too, and most of the original performance can be recovered from them with a little processing. I have 30-year-old cassettes that still play well, and 40-50 year old reel-reel tapes that play fine on my new-old-stock deck. Things do eventually die, though; I understand, for instance, that the original masters of the Solti Wagner Ring Cycle done by London in the 1950s-early 60s (one of the first major classical productions in stereo) are no longer usable - tape has deteriorated too much - but good-quality (probably 48K/16 or 24 bit which was studio standard at the time) digital transfers of them from the 1990s have been used for recent releases. I wouldn't be surprised if new analog archival masters were cut from those digital files and are now in a climate-controlled vault somewhere.

Another consideration: what's the lifetime of film/microfilm/fiche compared to, say, PDFs on CDs or DVDs or even hard disks? If you were presented with undamaged media and have no other information, how likely are you to be able to figure out how to read the data and how long would it take you? My guess: for the film, if you are in an industrial civilization, you could figure out how to light and enlarge it, and build the necessary gear, in a few weeks to months. Only knowledge of basic physical principles and precise fabrication capability are needed. For the digital stuff, it's gone forever unless you can find old paper documents describing how they operate and how the data are encoded, then build new-old computers and lasers and drives and write some serious software. Digital is not forever without constant management. Potentially, at least, analog is.