Not Quite Chaos
The singular person in charge of the project is the Kaitiaki. This is an elected position within the community, and very roughly translates to guardian of the sky, sea, and land. When I joined, that person was Pat Eyler. Nowadays, that person is Rachel Hamilton-Williams. This is less of a dictatorship, and more of a grass roots effort, but at the end of the day, the answer to the question "Who's in charge, anyway?" is the kaitiaki.
After that you have the release manager. The last release manager was Paul Poulain, the current release manager is Josh Ferraro.
One of the niftiest things about Koha is that folks stick around. We don't just have release managers, we have release maintainers. If you're a bit shy about upgrading, the chances are that there will be someone out there that still cares for and feeds your version. As always, it's best to upgrade, but the developers wanted folks to never feel orphaned.
In theory, if you wanted to know where things were, you'd check the release roadmap. It's perfectly valid to query the listserv about progress, though.