I hope that Medium deprecating support for custom domains will encourage folks to pull their content from there. I know I’m certainly thinking about it.
If people do pull out of Medium, it further decentralises publishing on the web, so it can only be a good thing.
Time to quell the myth that Medium brings traffic to your posts too. A recent rather successful one of mine had about 7% of traffic from the site it was published on. Not worth giving up ownership for is it?