The Wayback Machine is simply a methodology for maintaining the web-availability of documents “of a certain age.” As the initial publication date of the Plan was 1997, when the WWW was in its infancy, I have no problem with this access method. For example, just because I have to go to the underground stacks (several stories tall / deep) at Moffitt Library (at UC Berkeley) and find a (very) old book doesn’t mean its contents are invalid.
The US Highway System was not “replaced” by the Interstate System (Eisenhower’s National Defense Highway System). Rather, they co-exist. While there may be examples of numbered networks of transportation routes which are “wholesale deprecated,” we know about these if and when they happen: there is at least some public notice, if not fuss and fanfare. We would know about it (and are not presented with any evidence) if SF’s numbered bicycle network (or indeed even a single route of it) were deprecated. True, there was “the Great Renumbering” (of highway routes in California in 1964), a streamlining of legislative routes, the Interstate numbering harmonization and what we know today as “state routes” in our numbered highway system. But that didn’t eliminate, for example, “legislative routes,” (which were always unsigned), it merely clarified them.
Hundreds of people worked for decades to develop this numbered route network and San Francisco erected many (hundreds of?) signs, many remain today. This network did not simply fade out of existence, even if some signs were replaced with a (different) method of wayfinding.
Perhaps I should have phoned SFMTA and gotten answers, that would be definitive. So would proof that SF formally eliminated the network (or specific routes). And I don’t know why you choose the word “replacement” (of route signs with destination signs) when the city’s own description of them (I quote earlier in the thread) calls them additions (to the network), not replacements of it.
Again, you yourself offer that the numbered oval signs remain. I don’t want to get too lost in the weeds of history, like you, and I also don’t think OSM should have things which truly don’t exist. (Though things like proposals, invisible but actual borders and such are exceptions we agree as a community to continue to include, with limits).
Seems like we need some definitive authority on this topic from SFMTA themselves.
Edit: Page 31 of the (2019 BPR) document Minh linked immediately above this post states “Wayfinding, a system of information signs along key bike routes, helps keep people on the right track when bicycling to their destination.” Clearly, wayfinding signs do not “replace” signed, numbered routes. Rather, they are a supplemental aid.