What experience does the end-user see when there is a package they are using and it is unpublished? Is there some notification? Or do they just have the same deprecated package forever?
Nothing happens for them, they can continue to use the deprecated package until they uninstall it. Unpublishing a package just prevents new installations.
I’m also working with the Atom team to add a section to the docs answering a little more of the “package maintenance” style questions here: