I wouldn’t be surprised if some of those go out of use in a few hundred years, if not much earlier. There will probably be major conversion efforts going on at some point. The alternative, the above formats being maintained for eternity, would be somehow depressing.
They are all-but deprecated though: HTML 1.0 is much different from HTML5 (2014); XML is upgraded to XML 1.1 (2004) and most people use JSON nowadays; and ZIP is very inferior to gzip and 7-zip. We're lucky web browsers are strict with never remove compatibility for old sites, and ZIP is still used by macOS instead of .tar.gz for some reason.
Once something is mainstream and non-perishable, odds of it going away go down and it's foreseeable that it will be around for at least as long as it's already been around.
This effect is super strong in tech, for base technologies, with lots of integrations, especially around enterprise/governmental systems (which don't get changed unless someone makes a strong business case why the change makes more money) and consumer hardware (which tends to linger for aeons since it's so distributed).
Also, several other tiny insignificant Operating Systems like Android(/Linux) [apk files] and Windows [builtin explorer support]. Let's also not forget Java JAR files.
However, the threat of fubaring web media doesn't come from markup (HTML, XML, SGML) but from the complexity of CSS having gone rogue, and JS.
Or DRM. HTML still being used isn't going to help you when its wrapped up in an encrypted blob. We're not there yet (except for video) but you can bet there are plenty of actors who will jump at the chance.
The frame element has been completely removed, the hgroup element is gone, and so is the dir element. acronym is deprecated in favour of abbr. isindex, plaintext, xmp, and listing are all dead.
The attributes border, clear, background and bgcolor have all been removed by HTML, and shifted to be CSS' responsibility instead.
Just moving between EPUB 2 and EPUB 3, you lose the DAISY format support, and external resources. (EPUB2 let you use full URLs to specify parts hosted externally, like webpages, but EPUB3 requires itself to be self-contained. Not a bad change, but still a breaking change.) NCX replaces just using a HTML5 nav element, and a few more things.
All of those things mean that there _are_ technical documents that exist, that _aren't_ readable without some effort to update them.
The main thing is that information which is important to people will get converted to newer formats over time, just as old print books get reprinted if they're popular.
Vs. decent-quality old "dead tree" books, properly stored, can be ignored for centuries and still be perfectly fine.
You might want to ask a good historian or librarian about all the incredibly important (historically, to us, now) documents which we know existed, but we do not have, because there was no continuously-operated, high-budget "Holy Brothers of Document Preservation" monastery doing all the re-copy work needed to preserve them. (And maintain off-site backups in case of fire at the Monastery, and ...)
(If you aren't familiar - most of the materials used for documents in ancient times degrade fairly quickly. Unless (say) carefully stashed in a nice, dry cave in an arid climate. And even that stuff tends to be "crumble if you touch it" fragile.)
https://en.wikipedia.org/wiki/Yongle_Encyclopedia
:(
For every important historical work we have, there are several more, at least as important, that we know we're missing. And presumably even more that we've never heard of.
[0] https://lists.w3.org/Archives/Public/public-html-admin/2013A...
Those are all basically cosmetic/layout related, though. The text itself is still perfectly readable.
I very strongly disagree. The amount of technical overhead required to render a simple zipped XML from some storage medium is immense. Even if you store this on tape, you need a tape machine to read the bits. If you manage to pull this off, you won't get anything useful, because the XML is zipped. Decyphering a ZIP and translating it into bits which only make sense if you know that they represent binary numbers and must be read according to an obscure translation table (UTF-8) which is stored also digitally, someplace else, is more difficult than deciphering the enigma code, the hyroglyphs, and the Inca knot language combined. And even if you manage to pull off this unbelievable feat, you still require a parser, a renderer, a display or a printer to even get close to the possibility for a human to read it. For all of that, you not only need electricity, but the devices required are usually easily broken, and manufacturing them requires knowledge and a technical overhead (and also an amount of electricity) orders of magnitude larger than simply using them. Not to mention all the raw materials required to produce a display, a CPU, etc, which may simply be unavailable to future generations.
Now imagine humankind after a complete societal collapse. Tribe A finds, in some basement that survived the apocalypse, a collection of basic medical books. Tribe B finds, in another basement, a hard disk containing the entire Wikipedia, as a zipped XML file. Which culture is more likely to survive?
There's no way to really plan for it (prepping is a joke) and it slows down progress if we really do it.
At least the ASCII part should still be easily readable ? But not much of a relief for non-latin alphabet languages...
While that was certainly true at one time, Unicode text, HTML, XML, and ZIP files aren't going anywhere (or there'll be a collapse of society so thorough that print books are unlikely to survive, either).
EPUB books are basically XHTML and XML zipped up along with any external assets (e.g., images). There are nuances, but a DRM-free EPUB book should be readable indefinitely. You can check this out by unzipping the EPUB and looking at the files inside with a web browser (if you're doing it from a GUI, you will probably have to change the file extension to .zip first, so it unzips rather than opens in your ebook reader software).