Vi is in POSIX, it has been open source since 2002, and some version of it truly is on every UNIX system.
My point is that all the FUD about "exa" being deprecated is just that - FUD. It's still open source and it can be forked and carried on, just like vi did. The "exa/eza" forks might even be more compatible with each other than the various vi forks/rewrites out there, although admittedly exa is a much simpler tool.
I think we're witnessing a weird fetishization of POSIX and/or GNU coreutils, like they are the epitome of stability, compatibility and continuity, but if you look at them historically, they are not so different from all these Rust rewrites.