Although in some sense I consider myself a fan of pop culture, and even make that claim on this blog, it wouldn't take very much scrutiny of that idea to quickly learn that, in many respects, I'm rather behind the times. I'm only familiar with the popular music stars of today in the vaguest sense, I watch more television via Netflix than I do first-run episodes, and I spend more of my time in the car listening to Old Time Radio podcasts than I do to anything actually broadcast live.
That said, I find it rather fascinating how watching some of those rerun television shows, or listening to the old radio programs, demonstrates how things I once considered "old" really haven't been so long ago at all. For example, when Star Trek: The Next Generation first started out in 1987, the original Star Trek itself had only first started out some twenty-one years previously. While that seemed like a long time back then, I need only do the math to realize that twenty-four years have passed since TNG started. I'd say we're due for another spin-off (no, the new alternative-universe movies don't count!).
For a different kind of example, I grew up thinking of Sherlock Holmes as being set in the moderately distant past of the late 19th century. Although the time frame of those stories is inarguably more than 100 years ago today, listening to radio broadcasts of the 1940s—when every episode opens with the announcer visiting a retired Dr. Watson at his home to hear Watson tell another tale of an adventure he shared with Holmes in his youth—reminds me that 100+ years really isn't such a big deal (although now that I've caught up to episodes that aired in 1947, I'm really wondering how much longer they can maintain the illusion that Watson might still be alive. Although the Holmes canon doesn't give a definitive birthdate for Watson, Holmes scholars estimate he was born around 1852 based on the dates we do have, which would make Watson 95 years old by that time). Indeed, while modern Holmes stories are almost always set in Victorian England, some of the old Holmes movies starring Basil Rathbone—which take place in the then present-day World War II era—remind me that the Victorian era itself wasn't really the "past" when the original stories were written, but were indeed more or less the present of the time.
Of course, who am I to talk? I still think of Calvin and Hobbes as a comparatively recent comic strip, and it hasn't produced a new entry in 16 years (which itself is half again as long as the entire run of the series)!