Even now, you'll see people post an article here from five or six years ago. It might have 100 comments on it. Five or Six commenters might already be dead -- including the article's author.
Now multiply that by 50. Most of the net will end up being written by dead people.
I blogged about this a while back -- http://www.whattofix.com/blog/archives/2008/09/the_dead_spea...
That, barring a cataclysmic implosion of civilization, the internet archives being populated now will likely be available for perusal 10,000 years from now.
As a corollary thought, an interesting exercise might be to only generate content -- movies, essays, fiction, non-fiction, whatever -- that you think people 10,000 years from now will find interesting. How does this constrain what projects to undertake?
This is another reason to study history: so you can imagine what people a thousand years ago would have liked.
Somehow I feel compelled to add an evil laugh at this point.