Thank you, hippo, for your step by step recipe regarding how to best inform the Perl community that a module is deprecated.
I have begun to put together my thoughts regarding a review of the Switch module, including numerous links, most of which will come from the Perl Monks website.
(I was not aware that this was originally a Damian Conway module that programmers shouldn't use in production, because its purpose is to explore and prototype future core language features, as explained at Categorized Damian Modules.)