Typically when people talk about that, they mean they want to move from an approach where files have a location to an approach where files are queried based on

Typically when people talk about that, they mean they want to move from an approach where files have a location to an approach where files are queried based on metadata. So rather than going to /home/kaslai/images/ to (hopefully) see all my images, I'd instead query my filesystem, perhaps like /owner:kaslai/type:image. The specific syntax would need some serious thought, especially if we want to make it fairly ergonomic to slot in to existing systems. There are a large number of approaches that one could take. I'm personally a fan of a hybrid, where you could navigate to a location and then make queries on anything within that location. IMO one of the coolest features that such a filesystem could have is dealing with music. There's no perfect way to map CD rips to a hierarchical filesystem, but that wouldn't be a problem if I could just open a "directory" like /home/kaslai/music/?artist/?album/ which would automatically make virtual directories based on the artist and album, or I could just use /home/kaslai/music?artist=Smash\ Mouth to get a list of all 182 copies of All Star that I have in my library.