This is awfully condescending towards people in their twenties and younger.
> Want to indicate Settings or Setup to a twenty something? Show them a tool they've never used in their lives.
> If you don't know who Johnny Carson is, how could you know that this is a old-style microphone?
> No one under 30 has seen a Polaroid in years but we keep using them for icons.
We don't live in a cultural vacuum where everything that existed prior to our birth ceases to exist or be represented. We watch old movies, we watch old TV, we read old books and we see old photographs.
Some things go missing and some things stick around. The icons that stop having a useful meaning will either disappear or be transformed and some icons will come to be a somewhat abstract representation of what they do, even if they're based on things that existed in the past.
I don't understand people's obsession with telling everyone they should modernize their icons - if you think so, then you should do it. See how your users react.