While it is difficult to predict the future (in terms of durability of specific media or devices), maybe a look to the past can help to put things into perspective.
In my personal experience, I can still read all the various media formats I have worked with since 1980, and some which are significantly older than that: Paper tapes, 1960s magnetic tape, many floppy disk formats starting with Apple's proprietary DOS format, ZIP disks, various generations of optical disks and hard drives, old ROMs and EPROMs.
All the old media have held up very well. I hardly encounter unreadable optical or floppy disks -- and that includes the 40-year-old Apple floppies. To read them, either the right "vintage" devices are still available (my own old stuff still works, or I bought someone else's on ebay), or a new backwards compatible device is available (e.g. optical disk drives), or I can build something in hardware and/or software (did that for paper tape and for demodulating the old magnetic tape).
So my advice would be as simple as:
- Label and document your stuff well, so you remember what it is. Biggest danger of "data loss" in my experience...
- Store in a dry and cool place.
- Relax!