I have no opinions yet, currently this is just an information gathering expedition.
One idea which just came to me while typing this: we remove the library from the release but keep the repository on GitHub. Users who need the obsolete library can obtain it using this "modular boost" system, or using a package manager (or maybe these are both the same thing?) I'm not sure how the testing would work. Who would test the obsolete library? Maybe that responsibility passes to the author or maintainer. Do obsolete libraries receive version tags? All good questions, and I'm happy to hear everyone's thoughts.
I've been meaning to raise this. How about a procedure something like this: Status 1: Library is maintained and current. No change Status 2: Library is a "candidate for deprecation": this is where we ask the question on the mailing list (and perhaps elsewhere), should this library be marked as deprecated? In order to reach this point then the library must: a) Have no meaningful recent maintenance. b) Not be a major dependency of other Boost libraries. c) Not be a major dependency of other active FOSS projects (ie google search shows up nothing). If the answer comes back as "no" then we should at least try and have a bit of a bug sprint on the library (remember those?) and at least get CI back up to current standards and relevance. In fact this step alone may be useful in focusing minds on what needs to be done to keep useful but unmaintained libraries alive. If "yes" to deprecate, then move to status 3... Status 3: Library is deprecated: it should not be used in new code, it's documentation contains a clear admonishment to indicate it's status, and the library is moved into a separate index on the website for deprecated libraries. It is still shipped as part of the release. Status 4: Former Boost libraries. After a suitable amount of time deprecated, a library may be formally removed from Boost. This means that: a) we no longer include the library in our release tarballs, b) the library is moved to a new index category for "former boost libraries" c) we do one final github-only release of the libraries source, users may download and extract over the top of the rest of Boost at their own risk. And finally... There is no such thing as a dead library: any library can be resurrected back up to status 1 by some meaningful maintenance and/or an indication that it is still relevant. Hoping this helps yours, John.