[0xbadcafebee]

Assuming people want to keep using/maintaining the code, you just prove the original maintainer has either abandoned it or died, and then you contact the repository admins (i.e. CPAN). Make your case that the original maintainer is gone and they'll probably make you the new maintainer.

If nobody wants to maintain the old code, or the design wasn't ideal, often times people will create a "v2" or "-ng" rewrite of it and try to keep backwards compatibility. Then the people who made sub-modules can simply publish their modules on top of the new base module. Old code continues running with the old dependencies until somebody links the old code to the new base module.