I am a little ashamed that Nameko 3.0 still isn’t out of pre-release yet 
Thank you for this push and volunteering to help.
I think the biggest thing blocking release is better documentation. Nameko docs have not been updated for a long time and much has changed, especially in Nameko 3.0. It would be a disservice to the community to release 3.0 without considerably updated documentation.
I have an outline in mind for the new docs. A lot can be lifted from the existing ones, but some certainly needs writing from scratch. Give me two weeks to get the bare bones of it together, and then we can decide how and when to fill in the gaps.
Documentation may be the only thing blocking release. I would happy to make 3.0.0rc9 the final RC unless you think there’s anything critical that can’t wait for the subsequent release.
Two obvious candidates for possible inclusion in 3.0.0 are https://github.com/nameko/nameko/pull/652 and https://github.com/nameko/nameko/pull/647. While they are very close to done (although I still owe reviews on them both) they are significant features that I think need to be tested in RC releases for a while – so including them in 3.0.0 would introduce more delay.