Medium is no longer offering new custom domains as a feature. Instead, you can create a publication on Medium that will live on a medium.com/publication-name URL. Existing publications on custom do...
The amount of work required to support this feature should be exceedingly low. It’s probably a good indication that Medium won’t be around within a year or so.
This definitely signals the fact that Medium has moved toward the more silo end of the spectrum from a data ownership standpoint. While I might have recommended it with reservations as a potential IndieWeb solution, this change means I can’t recommend it at all.