This issue is a placeholder for discussion of the "At Risk" feature of host-meta based hub discovery.

https://w3c.github.io/websub/#discovery

The working group knows of no publishers that depend solely on the host-meta based discovery, and believes that all publishers offer discovery in either of the two other ways. If you have an implementation that is only able to advertise its hub via host-meta, please comment below.

There's an argument in #101 that host-meta for rel=hub is useless unless we also allow host-meta for rel=self (with templates) or allow rel=self to be optional.