The web is terribly large now but still terribly fragile.
Kitty could close down. Hundreds of original animated characters could simply disappear from human knowledge.
People could stop posting cute cat videos to YouTube.
Nah. Never happen.

I agree with Scott. The Wayback machine is an attempt, but imperfect; and not always easy to use. There was stuff on the web I really appreciated, but the person who put it up didn't/couldn't continue to support it, so it's gone damitol.
Libraries are imperfect, too. Yes, books last forever if not exposed to weather/bookworms/other disasters. But libraries run out of room and choose to get rid of "nobody read this stuff" books. When we first moved to this county, the library system had a lot of older (we're here talking early 20th century) "how to" books. I recall one about house building that contained the immortal line, "A man with a hammer and a (hand) saw can build a house by himself." Hand most modern youths that kind of toolkit, without a skilsaw, chopsaw, jobsite table saw, etc., and watch 'em faint. Having that historical perspective was helpful to me, although it also warped me into some prejudice agin modern tools that I've since come to appreciate for what they do. Still don't like framing nailers.