There has been talk on the internals forum of "gating" deprecated parts of the std on a new edition. So the deprecated feature will be hidden for crates that declare `edition = '2030'` but will be available for crates using an older edition. Essentially turning the warning into an error.
But this is just talk at the moment. Currently there is no mechanism to implement this. It would also be a challenge for documentation.
Yes; this is so far off, and is not even at the RFC stage, that I didn't mention it. But you're right that maybe, someday, we could make it even harder for folks to call these things in newer editions.
> could be eventually removed.
It can not be used according to our stability policy. There's a lot of closed source Rust out there.