What about everyone else using your code? You are going to ask them all to update their code as well? Many of them probably won't realize, and will get stuck on an old version that never gets updated, even to fix bugs and security issues.
The idea is: the package maintainer pushes a final version of the old package that is a shim, and which has a deprecation notice. The shim imports the new package, and forwards all calls to the new package (and I suppose type aliases and variable aliases as well). The shim includes `//go:fix inline` annotations on all exported symbols, so that when users run `go fix` it rewrites their code to use the new package, by inlining their usages of the old package (which is now simply a shim that references the new package).
Not perfect. There is still a bit of a discoverability problem. Not all tooling warns on deprecated packages/functions (go toolchain doesn't, but gopls and staticcheck do). And users need to know to run `go fix`.
1: https://go.dev/blog/inliner#example-renaming-ioutilreadfile
// Deprecated: use example.com/mod/v2 instead.
module example.com/mod