I think we should add HDBSCAN. the original paper is from 2013, @lmcinnes's accelerated version is from 2017, the original paper has 300 citations, the 2017 JOSS paper about the implementation has 100.
I think that should fulfill our requirements, and it's commonly asked for.

@lmcinnes said he might not have time to move it so maybe someone else can pick it up.

For reference:
https://github.com/scikit-learn-contrib/hdbscan