I was reading some old posts from a internet forum which was active around 1998. They posted a lot of photo's together with text, but these photo's aren't available anymore because, well, link-rot. So I wondered, what efforts are being made to retain the digital/analog context and the "whole" consciousness of today's society for future analysis?
The answer to your last question is the most important. No, it's not historians of today who think of this. It's librarians.
The things that librarians of today find important and decide, with their limited time, energy and funds, to preserve, is what makes it to the future. We can see this in an example from the past.
I had a professor who is a historian of medieval science, including pseudoscience. He was researching, I think, German alchemy. He finds a listing on a digital database for a huge collection of alchemical pamphlets in Germany, and is incredibly excited. Many of these pamphlets haven't survived in any other copies. So, he calls the library, and asks about them. With audible frustration, she tells him that all they have are the title pages.
A 19th century librarian had decided that these pamphlets were unimportant, but that the woodcuts on the title pages were worth saving. So, that person ripped the title pages off and saved those, after trashing the rest.
Hopefully, librarians of today are better trained, but decisions like these are what determine what is available to historians of the future.