Re: Good riddance
As originally conceived, there was a distinction between a Uniform Resource Name (a canonical identifier for the resource) and a Uniform Resource Locator (which identified a means of retrieving the resource). As I recall, TBL originally envisaged hyperlinks as being bidirectional to avoid the "link rot" problem.
Unfortunately, URNs ultimately require a directory provider (and agreed metadata and searching criteria) to find the associated URL(s) and bidirectional hyperlinks are largely impractical as it would be impossible to make a link without the consent of both "ends" not only to their creation but subsequent maintenance.
Instead of a URN directory, we first got the much simpler, but monolithic, search engine (the Internet has really struggled with distributed supplementary services - the fact that domain names are monetizable mean that DNS and TLS certificates are viable, but they're exceptions). These "solve" the problem of resource discovery in a different way: instead of looking for a specific resource, they attempt to identify available resources that may be relevant even if they're not the specific one you're looking for. They worked reasonably well in the past - at the cost of creating monopolies in information discovery - but are breaking down as it becomes harder to distinguish between authoritative content and spam.
Where information quality is important, you generally need something better. The Universities at Bath and Bristol - among many others - have been working on Resource Discovery Networks for years, but the issue is that human assessment of information quality is still the most effective.
I think there is a potential role for something between a link shortener and a URN: a service owned by an identifiable authority, with established criteria for cataloguing resources that could issue permanent "handles" for resources whose actual target could be transparently changed to match their present physical location. Those wouldn't just be academic authorities - you could have a service that accepted any resource if was offered, but it would be much easier to attribute a reliability score to the catalogue provider than to the individual documents. There could even be a delegation of authority similar to the X.509 chain of trust in security certificates.
I think there is possibly a financially-sustainable model in there somewhere, but the issues of finding and identifying resources, assessing their quality and capturing ephemera are all related and increasingly intractable problems to which better solutions are overdue.