Looking for (co-)maintainer
There's a lot of people who still use Mailchimp, and CiviCRM deserves a reliable and efficient sync extension, which this hopes to be. But it's complex and hard because the two systems work very different ways.
All my clients that currently use Mailchimp are considering moving to something else (CiviCRM + Mosaico or another 3rd party marketer), which means I will no longer be able to access funds to maintain this. I'm happy to chip in expertise but obviously I'll have to drop its priority on my availability.
Both of these are reasons to seek a co-maintainer(s), so if interested please leave a comment here.