I'd argue that if one wants to ensure that the whole lineage will be with us 20 years from now, the first step is to make sure that the software is still alive

I'd argue that if one wants to ensure that the whole lineage will be with us 20 years from now, the first step is to make sure that the software is still alive 20 years from now. And using a mailing list is a good way of starving your project to death, if you're not Git or Linux or Postgres. And I'm even worried about those... what will happen in a few years/decades from now, when the generation of devs that are using mailing lists is not active anymore?