When people write about long time storing of data, usually they discuss issues related to physical storage issues. Meanwhile, data formats are also very important. Just imagine, that you found your father dairy stored in format of text processor poplar in early 80x.
We have rather big family photo archive: it is organized in google picasa, we have jpegs, CR2 and NEFs there (and m4 for movies).
I’m pretty confident that jpeg format has good support in future. It is very popular, therefore migration to next “default” format will take long time and many tooling will be available. I cannot say the same the same about raw camera formats CR2 and NEF. They are very popular format, but not that popular as jpeg. Other RAW formats are more risky investment.
Recently Google discontinued picasa. This means, that when I replace my current notebook with newer one - I have a problem: where I can get picasa? Moreover, even if I keep local copy of picasa setup, very probably, few years later I will not be able to install picasa in actual windows. I’m lucky since we mostly never edit photos in picasa. We just mark best of them with a “star”. But even “star” label migration to another tool is not a trivial task.
For not that family photographs I use ubuntu and darktable. Darktable is very powerful non-destructive photo editor and organizer. For long term, this is even worse: in 20 years, I will have CR2 and NEF files, which, probably, will be supported by very few programs only and metadata information about applied darktable “tools” which will not be supported by any program, except darktable, if it will exist that time. Actually, already now one cannot migrate from one non-destructive (like lightroom, picasa, darktable, digikam) editor to another.
The funny thing is that very probably, less valuable photos which people just upload to free internet services are most secured. At least until the service is not discontinued, but even then one usually can download them back in actually relevant popular format.
So, most mainstream data (photos, text) in most mainstream formats (jpeg, txt, doc) are most secured. More exotic, more professional formats are more risky.
Meanwhile, I still cannot find picasa alternative to organize my family photo and video archive (I do not even need an edit feature in it).