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).