My dad dumped out a box of full of gold to put the pet rabbit in the box.
Later on the wtf hit. Why did I not just put the rabbit on top of the gold.
Pepper the rabbit lived a long and happy life though.
I really doubt there's a future where archivists lose the ability to open a pdf, doc, jpg, or png, even if those are not standard formats supported by OSes in the future. The data will likely be there and accessible, but it's unknown if the interest will be there. Attention is already stretched to an atom-thick sheet. If that trend continues I can't imagine people caring about things that happened last week, let alone last century (most of the time).
What I mean by that is, people probably only keep what is useful to them. And if your collection is seen as useful to some people in a couple decades isn't really easy to tell. Depends on the circumstances I'd say.
Though I think you can get a good idea by asking yourself questions like "what things of my grandfather's am I interested in?" and "what kinds of things of their grandfathers are people often interested in?"
Also, someone's always interested in genealogy. So I bet a short bio with a good photo, spread around in a few physical copies, will probably be preserved for quite some time.