After posting my previous post, I dug a little deeper and found a webring host still functioning Webringo.com. So if you have an idea for a ring you want to start you might give them a try.
I doubt they know about the Indieweb movements efforts to revive webrings. Maybe somebody from Indieweb should reach out to them and encourage participation. It looks like they are holding on as a hobby, but barely. A little encouragement might help.