No one ever considers the volume of photos and documents we are now creating. My parents probably took dozens of photographs when I was younger, and kept maybe one or two albums. Nowadays, most people have hundreds if not thousands of photographs and videos. So it seems to me that the converse will actually be true. If you've got a 100 fold increase in the number of documents and photos being created, and only 1% of those make it, you're still preserving the same number of documents. And frankly, I think that's a conservative number.

As some of the other posters here mentioned, with the advent of cloud based services and easy backup systems, retrieval is getting easier. So if storage and retrieval is solved, that leaves format evolution problems. But somehow I doubt in 20 years or even more that JPEG is somehow going to be harder to read than it is now.