I belive that in the technical world especially, all content has a shelf life. I have customers to my content management system that want to break the rules of the tool and create a document type that never expires. What are your thoughts.
True, everything is a "fad" in a way. The only thing I can ever see being considered "timeless" would be personal development and religious websites that talk about one thing: improving your life. Although, even those types of websites die off eventually. "Timeless" is really nonexistent.
There are timeless content as nusuni mentioned in religious. Like... "is there God", "Who created the World? and what was before that?", "What's the meaning of life?" etc. In the technical world it gets tougher to find timeless content...
What are you asking about? Content or file technical details? If you're talking about content, the term you're looking for is "evergreen". Essenticially content that will always (or just about always be correct). Content like facts on historical data, scientific content, etc... would generally be considered to be evergreen as it rarely requires updating.
Even in the tech area, there is a lot of evergreen content (for instance, writing about the history of pretty much anything won't change, especially if it's old school already and obsolete). Even things like reviews are pretty much evergreen, b/c they'll always have value, whether it's someone later looking to buy a used gadget and wanting the old review, or it being used comparitively later on versus new models released.
Humor is another area that can be considered timeless. Even within tech topics, there are some areas which are relatively stable compared to others - example,. tutorials for win98 or word97 are still useful. If your CMS requires a forced "end by", check what's the maximum possible - and whether that can be extended later. It's a manual workaround but better than nothing.....
I'd also have to wonder why on earth someone would use a cms that limited them like that, without at least leaving them an option to exercise control over their own site with some kind of workaround.
I would imagin that old content would die of a little, but then it will be good to use for history. Also, things like games, videos, images, etc will not really die as there are over 8 billion poeple in the world and there are new people getting into games everyday. Even with the classic games, they still get played by youngsters as they may seem old to us, but to them they have never probably played them before.