I would happily bet that 50 years from now, so long as you've preserved the bytes accurately, it will remain possible to open DRM-free PDF/A files, epubs, MP3s, JPEGs, PNGs, CSVs and zip files.

With well defined and documented file formats, and with OSS applications supporting them, they can be read for all eternity.

You don't need binary compatibility. You can load a gif on any computer today, and it's old. I can view aiff image files from my Amiga still.

We're already 50 years in on many formats.

Where it becomes uncertain, it DRM laden, closed source applications with bespoke file formats.

> There's no guarantee you'll be able to easily use an ebook in today's formats 50 years from now.

I have no idea what “easily” means here, but I’m not unique. While these open-format ebooks remain of interest to even a small community, they will remain readable and convertable.

What makes you doubt that?

> You're really that confident in 50 years you'll be able to easily run x86 applications written for Windows or Mac?

Again, I have no idea what “easily” means here. However, my use of “proper” also wasn’t clear (I edited it down from “free software”).

“Proper” certainly implies that their runnability does not depend on the wall clock, or availability of an internet service. Yes, I am confident that I can run such programs in the future, on appropriate hardware.

(Note how the thread is about digital, not physical, things.)

Do you have any examples of digital media/apps in open formats which are no longer accessible?