Fair point, let me clarify: “move” in the sense that future versions will live in another registry, and with a nice, user-friendly transition process and upgrade path.
Since Julia already supports URL dependency, a package registering to General is no longer the only way of promoting it. I think General should enforce a much stricter rule.
As for moving packages out of General, it could be achieved without breaking manifests by adding deprecation marks and redirecting.
URL dependencies aren’t first class deps though. E.g. they won’t be properly resolved transitively, and won’t do things like version resolution.
Maybe a key “language” in some section of Project.toml