My personal take is that this breaks down into two categories: Saving family photos for posterity, and museum-grade long term archiving. The two situations are very different.
I am mostly interested in preserving family photos. In that context, a bit of fading or degradation (while not desirable) is no big deal. Adds to the charm, in a way. Earlier this year I put together a photo montage for a funeral that involved scanning a shoebox full of old prints...from the 30's and 40's mostly. These were amateur, family snapshots. As such, most were not that strong technically in the first place, and time had taken a (minor) toll as well. But that didn't matter. It was still easy enough to see and recognize the people in the photos, and that's what mattered.
That's what troubles me about "the kids these days". They take a zillion iPhone photos and post them to Facebook or Instagram or (even worse) SnapChat, and not one of them will be accessible to their great grandkids. Zippo. Such a shame. 30 years ago, "taking pictures" meant film, sure, but more importantly, it meant prints. Every single shot was committed to paper. Most of those have been lost or destroyed, but many survive in shoeboxes or albums. Those will be around. In that sense, to me, this isn't about "digital v analog" so much as it is about "paper v monitor". Unless your casual photos are on paper, they are going away.
As for the museum-grade archiving, that's something else. If an institution (eg, Smithsonian, etal) has the resources, I'm sure there are all manner of reliable techniques for preserving both analog and digital photos in perpetuity. Perhaps there are techniques that amateurs and dedicated hobbyists can use for the same result, but that goes back to the human factor. Even if one is sufficiently dedicated to an active preservation strategy, its only as good as the person you hand it off to when you die. Absent some institutional persistence (such as a large museum), there is little reason to think such efforts will outlive the individual.
I'll leave such concerns to those who have a catalog worthy of the effort. I certainly don't. My "best" work is all printed out, and will probably fade or degrade with time. The most I can hope for is that maybe, someday, someone stumbles across one of my prints and finds it worthy of a moment of attention. Or not. I do this for me, not them.