I have a 286 that can take MFM drives. I've read 1982 HDD drives in 2004.
A PCI SCSI card and suitable PC for every kind of wire cable SCSI drive ever made, ditto IDE.
PC to read 3", 3.5", 5.25" Floppies (I gave away my 8" drives, with adaptor info for 3.5" controller).
I have PC software and bootable DOS to read about 1200 CP/M and other floppy formats.
I can read FAT, FAT32, NTFS (1993 to current), EXT2, EXT3, RieserFS, and other HDD formats.
I have a HW card to support reading pre -white book CDI video, there are many other CD formats that new Mac, Linux or Windows machine doesn't support any more, assuming it has an optical drive at all.
Flash (USB, CF, SD card etc) does fade in about 5 to 10 years unless re-written. A home written CD or worse DVD uses changes in a dye, only the grooves are pre-pressed. This will erase in days in daylight, especially DVD! The bought discs have the data pressed too, as pits in the groove, so even if the reflective layer rots or it de-laminates it can be repaired and read. Not so home 'burnt' writeable DVDs. The Magneto Optic discs were stable. Archival CDs (usually also gold coloured) use more expensive dye and are slower to write. They too should be be kept in the dark.
Floppies and HDD if in a dry atmosphere and not used (or kept powered) will last maybe 100 years. Perhaps months in the damp. All HDD unsealed. They have very fine dust filter on the air port. So vapour / gas mixed with air (cigarette tar, steam, SO2 ) can get in and corrode or contaminate the works or the magnetic surface. Larger and older HDD use aluminium substrate for the magnetic coating, smaller drives are usually coated glass.
Periodically read important archives on to new but reliable storage. Keep the old copy.
You really don't want to know about the costs and time involved with Tape Archives! I have 2 x kinds of linear tape and 1 kind helical tapes. I doubt any of the tape drives are working (though I have them). I think I have all the stuff on HDD.
Our server in 1994 was only 40Mbyte, now I have two, each with 2T byte. That's 2,000,000 Mbyte approx. each. I mirror between them and also use a USB SATA dock with a full spec NAS quality HDD to also back up. My first HDD was in 1982 and was 5 M Byte
All my own created content is on USB stick, 2 x laptops, server, back up drive and on my Hosting in a different country.
My CD collection is on a Micro SD card, Server, 2 x laptops, and a 160G Byte HDD in an Archos player. Eventually it may be cost effective to store all my video collection at full quality on HDD for easier access. I bought a Digital 8 camera some years ago and started digitising my own Analogue 8mm movies using it as a Firewire bridge. It's very time consuming though.