This specific problem is something I really want to work on. I love when @jennybryan annotates sunset sections of the STAT545 site, and have a few ideas (but nothing great 
) re a way of indicating "freshness" of packages and info.
I did a not-so-great job of asking about this on Twitter last week, but what I was trying to illustrate was the general idea of somehow noting "not new, but still good."
https://twitter.com/dataandme/status/906487697157623808
Better res. images here: https://imgur.com/a/kRGhG