It appears that WorldCat Identities links are no longer working. I remember the OCLC being explicit that WorldCat Identities was an experimental feature when I talked to them about it five years ago, so I'm not sure if it was taken down permanently. The links have not been working for me for the last few months though.

According to Wikipedia, "In May 2022, OCLC announced WorldCat Entities, a new infrastructure for library linked data. Maintenance of WorldCat Identities was suspended and the service will be discontinued as it is being replaced by WorldCat Entities."

https://en.wikipedia.org/wiki/WorldCat

What is unfortunate is that all of the data pulled through Identities doesn't seem to be available for Entities. It appears to be mostly for works/editions and doesn't cover all entities (bands, companies). Some already have them, like Elton John

https://id.oclc.org/worldcat/entity/E39PBJccbHHPj7T9XWcW9yBpT3.html

I suppose that the current WorldCat Identities links on MusicBrainz should be assigned to a bot to automatically add end dates? And then maybe a new MusicBrainz URL option can be added for Entities, like the one for Elton John above?