For example, yesterday I walked past someone wearing a T shirt with a graphic of John Cleese (as Basil Fawlty) saying "Don't mention the war".
To get the joke you not only have to know the show Fawlty Towers, you also have to understand a raft of context for World War II and the post-war issues between Britan and Germany - itself a mixture of nation regimes and people-to-people matters.
Quite a lot for a one-liner. As a cusp Boomer/GenX, I get it but I doubt many Xers would. What sense would a GenY or GenZ make of it? Well, that's partly the point here, not only that they wouldn't but also they just wouldn't bother with anything not targetted at them anyway.
Obviously this kind of cultural turnover is nothing new - our history is full of them. There are a lot in Shakespeare for example. To get all the jokes you need a well annotated and researched version.
Lewis Carroll is another example. I accidentally found out - via Heston's Feasts - that Turtle Soup was such a Victorian fancy that a cheaper seemalike of Mock Turtle Soup was very common. Common enough for Carroll to have a "Mock Turtle" character and never mention "Turtle Soup" at all. I'd misunderstood and thought he had invented the idea of a "mock" creature.
Note that I do want distinguish between a such historical effect and one based on breadth of knowledge. For example having recently read another Jasper Fforde novel, I'm sure there were plenty of references that I didn't get because I haven't read some of the required areas/genres. Here I can safely dismiss generational cues as Fforde is almost the same age as I am.
So much for the kind of cultural turnover that we can expect to observe as time passes and takes with it morsels of information and its tags. What about the idea that there are similar changes to peoples' general attitudes?
This is something that my partner and I have observed as we get around our lives. While we've noticed it in Perth, I'd be surprised if it isn't a general change throughout much of the Western world.
An example of this change would be the concept of taking a photograph. I had to explain to someone recently that most people now take photos of themselves rather than of other things. To this end, most mobile phones that have cameras also have a small convex reflector next to the lens. I advised how this allows the photographer/photographee to see how they will fit in the frame as they snap themselves from in front of the camera. As this issue involves new gadgets and new technology I note that it correlates well to the younger generations. Us oldies are less likely to want or notice such a feature.
Another example however which has clearly crept in and restrospectively been adopted across the generations is the related idea of where the entertainment is. To people who have shifted into the new mode, they ARE the entertainment - and a professionally created and presented show they attend is merely lucky to be there too.
We were recently at a performance of The Fabulous Flag Sisters in Fremantle and the row of people in front of us, while clearly enjoying the show, only had an awareness of, say 50% of it as the rest of time they were busy facing and talking to each other. I didn't mind, they also took time to interact with the show and added to the festive spirit. But it was miles away from my default attitude of being intent on watching in full the artistry I've paid to see.
I suspect that some of this change is based on economics. With an attitude of affluence, the new mode presumes that their pleasure is paramount and performances can be chosen for their convenience. It will be interesting to see if an economic downturn ever creates a reversal of that trend. Ideally of course there will be no downturn.
It is in combining these two shifts that I think we will see a total change in how culture is structured in society.
It may be that satire will be hardest hit as it seems the form most obviously dependent on commonly shared cultural knowledge. It may be no accident that general satirical sketch comedy has disappeared from television. Even in movies satire has become specialised - e.g. horror spoofs for horror fans etc.
There may never be another Monty Python equivalent because our social patterns have no place for one.
The process of referring to something via its conceptual content will be replaced by literal referencing - what Lucy said about Damien's comment on Susan talking about Zack etc - e.g. via a hyperlink on a blog.
In Literature, the oblique reference may also be doomed unless authors are prepared to provide their own footnotes.
The whole presumption of writer vs reader is going in the blender and may never settle back to how it was. There may need to be a smartening up among those who create in old ways, to counter-balance the supposed dumbing-down of the new. Simply presuming that your audience/readers know what you're on about is a luxury whose time has passed.
Performers who thrive on audience response may find that expecting lasting appreciation from consumers of their content is likely to be fraught with disappointment.
To quote Shakespeare, "O brave new world that has such people in it".