What's your idea?
Set up a community OAuth server that not only manages all the login to all the *.d.o server, but also allow third parties to authenticate against it. Particularly community oriented sites such as http://www.drupal8multilingual.org/ would greatly benefit from this.
The same server can then also be used for improved and centralized management of user profiles etc.
What are the benefits?
Make login in to *.d.o sites much easier and with greater UX. Allow users to make sure their community user name can be used on all sites allowing authentication via the community server.
What are the risks?
How can we measure the impact of this idea? (metrics)
Who directly benefits from / will use this improvement? (target audiences)
Are additional resources available for discovery/implementation? (volunteer effort, financial backing, etc.)
OAuth2 server module already exists https://drupal.org/project/oauth2_server