John Maddock wrote:

"Unmaintained": speaks for itself, the library is important enough to keep around, but has no maintainer. We need a procedure for acquiring new maintainers, but traditionally we've recruited from existing authors who are a small, and rather busy pool of people. The alternative is to recruit from outside, but we often get enthusiastic, but not very experienced people coming forward. Getting them to submit PR's and having an experienced old hand check them through is very time consuming and unsatisfactory for both parties.

Taking over unmaintained libraries is a problem that, in my opinion, has no solution. Even an experienced person such as myself has trouble evolving existing libraries without the deep knowledge of the design decisions that resulted in their current state. In addition, every new maintainer inevitably wants (and needs) his work to matter, whereas maintaining a legacy library is thankless work that leaves no room for creative expression.