I still have an 8 inch floppy disk, but I have not seen a reader for way over 30 years...
That's true, but...
There is a big difference in the
scale of deployment with 8-inch floppy discs (and ZIP disks and MiniDiscs and DAT tapes and so on and so forth). We've sold a
metric ton of computers with optical disc drives over the past 25 years or so that they've been prevalent. I bet there were points where they were selling more computers in a single day with optical drives than were ever sold combined with 8-inch floppies.
That's called a hockey-stick growth curve, and it is why Bill Gates runs a foundation and fights childhood malaria.
So, while it might be getting a little hard to find a player for your minidiscs and even 5 1/4 inch floppies are probably mostly found on eBay and Craigslist, you can still buy a brand-new turntable for entirely too much money. And, I suspect, that optical media (CD and DVD, if nothing else) will have a similarly long-tail. If only because of sheer volume. Even if they stop making them entirely, there are just so many out there, that I don't think it will become a serious challenge to find one if you want one within my lifetime.
It is far more likely that it'll become challenging to find a way to hook it up to a computer, but a USB > PATA/SATA cable dongle will last a long time and until they break USB backwards compatibility or abandon it entirely, and all of the computers that support the old standard break, I think it has a pretty long-tail.
On the other hand, of course, will software even read the file formats anymore? Who knows? (Certainly not if it has DRM, which is my main problem with DRM.) Stuff does die, and sometimes unexpectedly. And, if you're saying "archival" needs to be available like the Bill of Rights... Not forever, but 150 years or longer? Well, then, obviously you're right.
I bet it'll be a long-long time, though, before it will become impossible to transfer your old collection of
pressed CDs and DVDs, assuming you can store them well, to whatever new whiz-bang three-dimensional data cube of the future we have that we plug directly into our abdomens, or whatever. I could be wrong, and I agree it is generally laughable that they call
dye-based discs archival, but...
I guess I'd say the concept of archival storage is a bit outmoded. Computer filesystems absolutely have their problems, and we're going to have a lot of stumbling blocks getting there, but... If we don't hit some crazy physical wall that it is impossible by any means to surpass, or we blow ourselves into the stone age, storage density
will eventually hit the point where it is possible to store the position of every atom in the universe (or something that gives us practically that kind of power). All storage will
eventually become indistinguishable from the network, and will be infinite and everlasting.
We no longer need to keep data forever in one medium. We need to keep it long enough, and in a convenient enough format, that it is possible to migrate to future storage systems, until the problem is solved forever.