I agree with Noam that retiring a package should start questions about what role this software currently plays. How many people use it, what are likely issues with the software disappearing, etc? There are also different reasons why a software could go into this mode:
The package was primarily an API package. That API has now disappeared, so without that input hose of data, the package can do nothing further. In this case, repostatus badge, archive on CRAN, and possibly also Zenodo. This is important because if any papers depended on this software and someone had questions on how the data was processed, they could refer to the archived code to discover any problems or artifacts.
If the issue is that the maintainer is no longer interested, then we could move it to a maintainer-wanted status and advertise that to others from that domain who may have an interest. Until then, it goes into holding.
If a package is a critical piece of rOpenSci infrastructure, then rOpenSci staff will take over maintenance, or actively hire a contractor for the process. But this determination will have to come from the staff. With the growing number of packages that are user contributed, we have to make the determination on how best to proceed on a case by case basis.