Whatever you enjoy—television shows, books, music, online media—is going to be forgotten. In twenty years, let alone a hundred, it will sit in university collections or landfills, abandoned.
It fascinates me what cultures choose to remember, and what they don't. Looking back on history, only a small handful of writing or artwork is ever preserved from an era. More is retained by scholars, but not by the masses. Most people could likely name one or two books from the 19th century—and those are the ones that were later turned not just into films, but enshrined in pop culture memetics, endlessly recalled by endless repetition. Dracula? Frankenstein? The average person might not even realize that those were originally books. Great Expectations would be seriously pushing it. Historical memory has miniscule bandwidth, and that which it does retain comes to represent and speak for its entire era.
Of course, there's no way that anyone, save university specialists, librarians or professional writers, can catalog and uphold that much information. So only a few works are kept in memory. It's often unexpected texts, since the values of future cultures will not be the same as prior ones. All cultures look to the past to find antecedents of themselves, or works that uphold their values, and so it's often writers and artists who were rejected in their own time that are selected, and upheld as "people like us"—for a time, at least, until the wheel turns again.
The 19th century was a time of explosive cultural output, yet it is like a Tibetan sand mandala, scattered by time, save a few works chosen to represent that era by stereotype. Even those few gems are at risk—witness the current Stalinist fad for invasive revision or outright censorship of older works. (For instance, the recent publisher rewrites of Ian Fleming and Roald Dahl's works to fit 2020s liberal American sensibilities, or the fixation of college literature departments on consigning the works of "dead white men" to the pyre, starting with Shakespeare. Likewise, the vast campaign of book-banning currently being conducted by Republican-dominated school boards across the country.) Our present culture, defined by information and genetic technology completely unknown to prior generations—and thus cut loose from the moorings of history—finds none of its values in the past, and so decides to deface and overwrite it, like the Khmer Rouge instituting Year Zero. A culture cut off from its past has no future, save whatever the current regime feels in the mood for.
It's a compelling, yet probably doomed, exercise to speculate as to what works from our present time—the most information and media-saturated in human history, by vast orders of magnitude—will survive.
I suspect that the Harry Potter books will likely still be read in the future (though the censors have already come for those, liberal attitudes from the 1990s now considered as conservative as those of the 1890s); those were an unparalleled literary phenomenon, mirroring the explosive success that Bram Stoker's Dracula enjoyed in 1897. We still read Dracula, and that story still exercises profound and enduring influence on our culture, and I suspect that Harry Potter might have a similar trajectory.
I draw a blank on any television shows that will survive. Maybe Twin Peaks. I think that show has enduring popularity not because of its pivotal historical importance to the television medium, and not because of its quality (which was far from perfect). I think it endures because it captured our culture in the moment that we were able to look with nostalgia on an older epoch of America, decide it was false and corrupted, and then both reject and fetishize it. It affirms us in our postmodern smugness, lies to us that we are smarter, better, clever-er, and I think that it will continue to appeal into the future as a time capsule of the historical processes of 20th century America. Or maybe The Simpsons would be a better candidate, and for much the same reasons.
Films and music I have no compelling thoughts on, although Piero Scaruffi's website might be a good place to go hunting for clues.
Finally, I think that the truly enduring document of this millennial period will probably be "Industrial Society and Its Future," by the just-departed Ted Kaczynski, and if I had to put money on any of this, it would be on that document surviving, and no other.
Widely rejected due to the violent actions of its author, I suspect that only Kaczynski's infamous essay will have any real explanatory power to future historians trying to understand what happened at the turn of the millennium. It is one of the constants of history that the works rejected by a culture as antithetical to their carefully-manicured self image end up becoming cornerstones of future generations, who will have inevitably turned the great wheel of ideology 180º by then.
The great hope for the Internet was that it would collate and preserve humanity's intellectual heritage, but what was missed was that this collating would be done on behalf of large language models, not individual readers. All of it will now just be grist for the mill in the AI-dominated future. And in that future, the document that was a final warning post to turn back before it's too late will undoubtably endure. The rest will be remembered and curated for us by ChatGPT's successors, and the work of preserving cultural memory will be left not to our culture's elders, but to Python code running on racks of graphics cards in corporate server farms. Corporations in the business of telling us only what they want us to hear, remembering for us only what they want us to remember. The freer world, the wider world, the world of possibilty—that will be gone.
Preserve your history. Hoard books, before the censors can come for them, or they are simply lost. (Numerous films from the early 20th century are already considered gone forever.) That which is preserved by you, is preserved for you. History will decide the rest.