Back in mid-2019, IBM took down their old IBM Library Server mainframe documentation website – http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/library – it was absolutely fascinating, it had documentation on mainframe products going back to the 1990s, and even other random stuff like a bunch of obscure IBM software packages for OS/2. Their new mainframe documentation site only has recent releases on it, it is missing all the old stuff.

So given that example, I doubt this is going to continue forever either. Sooner or later someone is going to say "FTP is a security risk, we need to replace it with SFTP". And then the old FTP site will disappear and be replaced with a new SFTP site with far less content. Or the hardware it is running on will fail and be too old to be replaced. Or someone will complain the OS or FTP server software are out of support and that makes them a security risk. The whole thing is only an audit away from oblivion.