Paper degrades, too. It’s just a different time scale. For long-term storage, you need to jump from one format to the next in as lossless a way as you can manage. This is not news: Libraries and librarians (well, those concerned with archiving) have known this for decades, if not centuries, and have been doing the newsprint-to-micro-stuff dance and others since before computers were widely used in libraries. The difference with digital is that ‘lossless’ is no longer a pipe dream as long as you don’t do something dumb like store your stuff in a format with DRM attached that you cannot crack. Luckily, DRM people can’t crack is nonexistent. Aren’t allowed to is a different story, but, hey, pirates to the rescue.
Another approach to this would be to use a self-unpacking symbology, like some of the approaches that have been designed with interstellar communication in mind.
However, this probably does impose limits on what you can talk about in the document.
And the oldest paragraphs preserved in Spanish are from the 11th century but I can understand them just fine, and the greater difficulty of the Cantar de Mío Cid (c. 1200) is the amount of technical words which have fallen out of use. I can’t write or speak Latin (I only took a year and it’s been a long time), but we borrowed an upperclassman’s De bello gallico just for kicks at the beginning of that year of Latin and, while we certainly wouldn’t have been able to produce a translation, we were surprised at the amount we understood.
English has changed a lot more than Spanish (or Italian, or French, or Catalan, or Portuguese); I have no idea what are the relative change speeds of other languages, but I’ve long wondered whether it’s English that’s the outlier.
That has been a problem, certainly. But it’s an easy problem to solve, once you’re aware of it, and folks now are aware of it. I’d bet money that data in electronic format right now is a lot more likely to last for more than a century than data on paper. The electronic data surely won’t be stored on the same physical medium a century from now, but it’s much, much easier to transfer it to new media as it becomes available than it is for paper. Even with a xerographic copier or the like, you have to copy each page individually, which takes a very long time, as opposed to copying the equivalent file in a fraction of a second.
On the topic of stable languages, meanwhile, I’ve heard that modern Icelandic is not just mutually intelligible with, but identical to, the Icelandic of the ancient sagas. I’m not sure why that would be, though, since so far as I know the language doesn’t have any religious significance like Arabic does.
Sunspace, I am inordinately happy to see that you got to post this.
That was cool to read. And I got the gist of it, if not the entire text. It probably helps that I also know French, and recognized the word “magjara”/Magyar. 
I suspect that in 1000 years people / androids / whatever with the inclination to study our era will know more about us and our language than we do.
This is one of those situations where there is not a symmetry between past and future. We have difficulty finding out some things about the past because few records were kept at the time, they were generally written on perishable materials, and often many spoken languages were barely written down at all.
Whereas in our era we record many trillions of times the amount of data, in thousands of different types of media, and data is continually being transferred from one media to another (so it’s not like existing media need to last 1000 years, though some may).
It’s rather like how it is difficult for me to research some aspects of what I was doing 25 years ago, but I will have no problem in 25 years time finding out virtually everything about my life right now.
la hungara is also an acceptable word for “Hungarian” [language].
Easy - you write it like an Ikea furniture assembly manual: all pictures, no words.
50,000 years from now everything we’ve ever written will be total gibberish to all but scholars and translation algorithms, but any idiot could assemble a goddamn Ikea bedframe in an hour flat, no problem.
Write like Yoda, you must, for live forever, Star Wars shall.
Dankon!
Chinese started out as pictures, and look where they are now. 
Becuase Icelandic linguistic purism is the law.
Seriously. Iceland has a law that new Icelandic words have to be based on old Icelandic words, thus keeping the language “pure.” (though loaner words do creep in). I think it’s really cool.
ETA: So 1000 years from now, Icelanders will be able to understand anything written today in Icelandic.
A letter written in binary language would most likely survive any changes in language.
Binary language? What’s that?
Yeah, there’s no such thing as “binary language.” There’s only binary code. The assignment of a particular character such as the letter ‘A’ to a particular binary number is arbitrary, there already have been more than one code, and a new code could be invented to replace them any time.
But maybe ASCII will still be used 1000 years from now. A set of three numbers canj be recognised as meaning ‘c’ ‘a’ and ‘t’. But the word ‘cat’ will probably be known only to a few scholars of ancient languages.
Then again, French has a similar law, but it doesn’t actually work, since you can’t throw people in jail for using the “wrong” words. And for any single law to stay in place for over a millennium is itself remarkable, and points towards some underlying reason.
I think there’s a widespread misunderstanding on this board and elsewhere of the normative role of the Académie in respect of the French language. French evolves like any other language and the Académie does not “lay down the law”; it merely advises on correct usage and compiles a dictionary. Its advice is routinely ignored, for example when it decided that “oignon” should be spelt “ognon”.
For this reason I think people are wrong to say “English is different from other languages (French, Spanish) because it doesn’t have an Academy”. The main effect of an academy seems to be to make people subtly less confident in the correctness of their own speech, and to make them question whether something is “a real word”. But there are plenty of sources of prescriptivism in English too that achieve the same effect without a centralised academy.
I was thinking about this recently. My daughter is a big reader, but she doesn’t like to read older books. She says the writing is weird. It’s true. There is a different style to the writing in a Nancy Drew book compared to something like Harry Potter. Kids get used to the more modern style and the older books get ignored. I imagine her grandchildren will think the writing in Harry Potter is weird too.
Think about ancient Egyptian: Thousands of texts carved in stone and desert-preserved papyrus over thousands of years - and then it was just forgotten. All those monuments sitting in plain sight and still folks just stopped caring enough to remember how to read them. If not for the lucky fact that Coptic held on long enough for someone to finally come along and give a damn, Egyptian might have been lost forever.
Civilization doesn’t have to fall (or fall very far) for a lot of knowledge to get lost. There just has to be an interest gap.