Yeah, this is nice. I bet something like this could easily be brought to systems like Arch/Pacman and NixOS/Nix if someone wanted to champion coming up with an implementation for those systems.
(Actually, this is definitely doable on Nix, since there are mechanisms like "insecure" packages, but 1. I dunno if there's any for this situation (block package without explicit confirmation because it's not maintained) 2. I don't think there's any policy for this, but it would be nice if there was at least a procedure for people who wanted this kind of deprecation. It's also a bit different on Nix since it is not a rolling release distribution.)
NixOS recently introduced "problem" infrastructure to deal with such problems more gracefully and explicitly:
https://github.com/NixOS/rfcs/blob/master/rfcs/0127-issues-w...
Completely agree. This seems a really nice approach in Gentoo. Am a big fan of Arch but I was immediately thinking this would be handy there - I'm pleased with the engagement/responsibility that Arch encourages but this kind of thing is always catching me out and I pay a fair amount of attention to my installations!