Two researchers studied PyPI's sustainability to understand problems that affect FOSS infrastructure sustainability in general. On Thursday 20 Aug (2:30 - 3:45 PM EDT), one of the study's authors will speak in a Ford Foundation event about FOSS sustainability: https://www.eventbrite.com/e/digital-infrastructure-labor-roles-and-incentiv...
You can read the researchers' report at https://github.com/FOSSRIT/mismatches/blob/master/Mismatches%20Final%20repor... . Key section of the summary:
These results suggest that different strategies are needed for addressing the non-technical capacities of digital FOSS infrastructure projects. While capacity for things such as documentation, outreach, project management, design, legal work, etc. are often acknowledged as needs within FOSS communities at-large, they are rarely addressed proactively. Rather, they are often addressed only when a project is in crisis.
I also draw your attention to the table of tensions between "FOSS culture" and "Infrastructure culture" on page 7, and the misperception that capacity-building may seem to be slowing a project down (p 6-7).
(Disclosure: I was a consultant on this analysis.)