No, the interweb is NOT forever.
Recently I have run into several people frantic to find something that used to be on some site. Sadly for them, the stuff is gone. And unless someone bothered to save it many years ago it is gone forever.
An old saying goes to the effect that "once something is posted to the web it's there forever."
Not true. It was assumed that things would forever stay in circulation on some server somewhere or be reposted constantly but that seldom happens. Even attempts to fill the gap, like the Wayback Machine, aren't coping with it well.
One can go into many shops across the land and find old books, magazines, even papers, from decades and centuries past but the outpourings to the electronic world are only slightly less perishable than the electrons it takes to transmit them. Links in news stories can become invalid in a few hours, even minutes.
Servers get replaced, fail, sold out, auto-expired, stop paying their registrations, etc. Many valuable sites and archives have died in the last few years. Once the person who put them up stops propping them up they disappear. They may reside on some drive or DVD somewhere (probably in a landfill) but they no longer serve the web.
Of course, the saying was never meant to be either all-inclusive or literally true. It mainly was a caution about putting embarrassing stuff on the web. You can bet someone will save that humiliating picture (burnthechair.jpg anyone?) or that poorly-considered revelation and repost it wherever it will hurt the most. And as often as needed.
But this has always been true. People were more cautious in days gone by and never used to put their lives on billboards or TV but the coziness of the keyboard and screen removed that inhibition. It was suddenly like writing to a close friend or relative. Or a drunken game of "I can top that." Only it wasn't confined to the den or the bar, it was in a crowded stadium, up on the Jumbotron.
So we have the worst of both worlds. Valuable info dies quickly but frivolous and harmful things live darn near forever because people take pains to preserve them.
Not really new. We have lost the great works of ancient Greece and Rome but the graffiti still remains.