I think the sentiment of the song is timeless, but the lyric's timelessness is running out. I mean, no kid under twenty, if randomly asked on the street would know who Brenda Frazier, J. Edgar Hoover, or wally (of Wally's affair) is.
The song is brilliant however if you are approching it with a 1970's time of reference.
I would love for Sondheim to recreate lyrics for a newer version, 40 years in the future from when the song originally took place, with all the current events that have happened since the song was written.
"I'm an American, Damnit!!! And if it's three things I don't believe in, it's quitting and math."