Removal of filesystem support: downsides

Even if conversion is only supported for ~7 years or so, you can boot an image from within that timeframe, convert the data to the newer archive format, boot the NEXT one you need a decade later, convert to the next format, etc. On any unixoid you can almost always manage to write a tarball to an NFS mount, or pipe it through uuencode to an emulated serial device being written to a file, or some such.

Storage getting bigger makes old block devices easier to image, and a proper data recovery setup will have snapshots of things like the devuan "pool1.iso" file so the servers having gone away no longer matter even if you need a weird obscure tool out of the repository:
https://ftp.nluug.nl/pub/os/Linux/distr/devuan/devuan_chi...

And you can usually dig up really _old_ stuff if you know where to look... https://archive.download.redhat.com/pub/redhat/linux/