Watching Star Wars today is like watching It's a Wonderful Life (1946) in 1977 ...
Listening to Nirvana's Smells Like Teen Spirit today is equivalent to playing Terry Jack's Seasons In The Sun (1974) in 1991.
Watching The Godfather today is like watching Charlie Chaplin's Modern Times (1936) in 1972.
To me, the most telling/shocking example is Back to Future. Kottke notes that watching it today is like watching 1962's To Kill a Mockingbird in 1985. But here's the more frightening point: In just seven years, we will be as distant from the Marty McFly Eighties as that era was from the George McFly 1950s. Which means that to achieve the same narrative effect, a Back to the Future remake that came out in the Obama Administration would have to send its leading man hurtling back through time to ... 1985.
As Marty might say: Heavy.