Why oh why did the programmers drop Fire Wire?, it was something that worked extremely well for all of the home video buffs who used DV & Mini DV cameras, as the saying goes, "if it's not broken, don't fix it", there are thousands of people out there who own DV cameras, including myself, along with thousands of DV cassettes which due to the totally thoughtless actions of the programmers are now rendered useless, Kdenlive was my editing suite of choice until the rug was pulled from under my feet, now it has caused me a great deal of trouble trying unsuccessfully to find a way around it, I know that the programmers have to find new ways to ensure a colossal amount of cash keeps flowing into the coffers, however, it should not be done to the detriment of the faithful who relied on that program, I have searched on line and found many people who are desperately trying to overcome this problem and those many people are just the tip of the iceberg, most of the material recorded on my tapes are of sentimental value as they contain a considerable footage of my late fiance which I would so much like to burn to DVD's, I expect the same sort of sentiment applies to many of the people that have been hurt by the total lack of feeling towards them, somehow, it doesn't seem to matter to the people who carry out these horrendous changes which bring about such unhappiness, we can only hope that one day they may wake up and smell the coffee, most computer manufacturers, do not now include a Fire Wire port in their new models which I firmly believe is due to the fact that Fire Wire has been dropped rendering it pointless to include such a port, I and perhaps thousands of previous users live in hope that those who thought it prudent to drop Fire Wire, will one day see the error of their ways and bring happiness back to all of those they have upset, I will not hold my breath.

I mean, as you said, FireWire has been dead for a decade... I hadn't heard of it since like 2014, so it's understandable it's been dropped (i didn't even know it was a thing with kdenlive). But you can download old versions here: https://files.kde.org/kdenlive/release/

I also have MiniDV Tape Cameras, and I miss Firewire also. I got a new Computer between Christmas and New year in 2020, and I had to install an IEEE 1394 card on the MB because the Motherboard did not have it on it. Linux Mint is my Daily Operating System, but to get this card working I had to install what I consider the worst OS in the World, Windows 10, and other than install it and install the drivers for a Sound Card I installed and this firewire card, I have never opened that OS since installation. I had to do this because the cards I bought only came with a Windows installation disk, and I contacted them, and they had no Linux Support whatsoever. So I have that Windows on there so that those cards work when I am on the Linux Mint side of My Operating Systems. It also works on the Ubuntu Studio side, and I have Solus on the OS List as well installed on my computer, but I do not do anything related to Video Editing or picture editing on that OS

Like Arkengheist says... old format.. old interface ... old Kdenlive... i have some customers with a typography shop that have PLOTTERS connected to 1995 computer just to have Windows 95 and a centronics port... if the DV is an essential format you have also to maintain a player .. like who love "33 rpm vinyls" ...
BTW i also have VHS and DV records... but i'm sure to find a computer on the trash on next 10 years able to run Windows 7...a and a capture card, in case i want to convert everything (when I retire ?)