Ok, that is a legit use case. It's been a long time since I've needed firmware that was FTP only, but I can see that possibility. But I still disagree with this:
> The consequence will be that many ftp servers still hosting software/firmware for legacy products will be taken down and their content lost.
Even if all the browsers dropped support for FTP, Finder and Explorer both have native FTP support, and there are plenty of clients otherwise. I doubt those resources will be taken offline.
ftp://ftp.kontron.com/Products/Motherboards/Industrial/D3544-S_Mini-STX/Documentation/ ftp://ftp.panasonic.com/pub/panasonic/call_center/firmware/
One advantage of ftp is that it is much easier to have access control on different resources than dealing with .htaccess files so it was popular with customer service.
The consequence will be that many ftp servers still hosting software/firmware for legacy products will be taken down and their content lost.