We've started a non-profit to deal with such issues. It's a lot of work, but well worthwhile in the long term because part of the process is clarifying such issues, and the organization keeps on existing regardless of any individual member.

Still, even this situation is much better than what we had before. It's on github and so the project doesn't randomly vanish from existence when the owner isn't there to maintain the machine in their closet anymore. Contributors see each other and can realize "Hey, maintainer isn't active anymore but there's still interest in the project, maybe we should do something about this".