I'm not the GP, but I think I can answer for AFS. To this day, nothing has come along that handles the global-scale filesystem use case as well as AFS did way

I'm not the GP, but I think I can answer for AFS. To this day, nothing has come along that handles the global-scale filesystem use case as well as AFS did way back when. What we have instead are these: * Parallel filesystems that fall apart at more than a few ms latency. * Geo-distributed filesystems that are too slow/insecure/unstable to be useful for anything that really matters. * Ways to sync separate remote filesystems, but with no pretense of consistency. * Things that don't satisfy even basic filesystem semantics (e.g. object stores). * Things that are proprietary, and thus useless/irrelevant outside of their originating organizations (e.g. Google). That's why there are still some very large installations of AFS or its lineal descendants; I know of one that's 50K+ machines. I once had a dream of creating such a successor, but have largely abandoned it. It's not that the technical challenges aren't both interesting and solvable. It's more that the financial, logistical, and personnel aspects of getting such a difficult project completed and used by anyone would drown out all of the fun. I know a few others who have reached the same conclusion, sometimes up front and sometimes after losing years to the effort. The only way such a thing will ever get done is if some deep-pockets org needs it enough to fund and support its development, while also being fully committed to open source. Unfortunately, every org with such capability seems satisfied with one of the alternatives mentioned above.