[updated 4/11/2018 ]
Link rot is a perpetual problem with the internet. We all have experienced plenty of occasions where a promising link turns out to be a ‘404’. There is something of a transient nature about the internet. Items can be moved. Servers crash. Domains are abandoned. Articles are lost. Nothing really is certain.
Another layer of certainty that probably needs to be reviewed is the uncertainty regarding link shortening services. This was highlighted recently by an announcement by Bitly.com that they are going to be retiring their link bundling service. This particular feature has apparently not been an overwhelming hit and the company has decided to retire the service rather than keep it up.