Link Rot is a serious problem for the internet in general. From Gwern:
http://www.gwern.net/Archiving%20URLs>In a 2003 experiment, Fetterly et al. discovered that about one link out of every 200 disappeared each week from the Internet. McCown et al 2005 discovered that half of the URLs cited in D-Lib Magazine articles were no longer accessible 10 years after publication [the irony!], and other studies have shown link rot in academic literature to be even worse... Nelson and Allen... examined link rot in digital libraries and found that about 3% of the objects were no longer accessible after one year.
>Bruce Schneier remarks that one friend experienced 50% linkrot in one of his pages over less than 9 years (not that the situation was any better in 1998), and that his own blog posts link to news articles that go dead in days; Vitorio checks bookmarks from 1997, finding that hand-checking indicates a total link rot of 91% with only half of the dead available in sources like the Internet Archive; the Internet Archive itself has estimated the average lifespan of a Web page at 100 days. A Science study looked at articles in prestigious journals; they didn’t use many Internet links, but when they did, 2 years later ~13% were dead. The French company Linterweb studied external links on the French Wikipedia before setting up their cache of French external links, and found - back in 2008 - already 5% were dead. (The English Wikipedia has seen a 2010-2011 spike from a few thousand dead links to ~110,000 out of ~17.5m live links.) The dismal studies just go on and on and on (and on). Even in a highly stable, funded, curated environment, link rot happens anyway. For example, about 11% of Arab Spring-related tweets were gone within a year (even though Twitter is - currently - still around).
>My specific target date is 2070, 60 years from now... Even at the lowest estimate of 3% annual linkrot, few will survive to 2070. If each link has a 97% chance of surviving each year, then the chance a link will be alive in 2070 is... ≈0.16 (or to put it another way, an 84% chance any given link will die)... If we try to predict using a more reasonable estimate of 50% linkrot, then an average of 0 links will survive... It would be a good idea to simply assume that no link will survive.