It's a good point, though I think JPEG, or at least code to read it will be around in 30yrs.
I've recently hit this myself. I've been going through everything since the late 1980s and archiving it. Every floppy, every harddisk, everthing.
First PC was a tandy 1000 and I had a lot of drawings I did, PNT, files, nothing reads those. I also had a bunch of .art files, from a freeware long dead art program (VGA Art Studio) which supported no other format. Luckily, the latter install had some (partially wrong) info on the format, so I had to in both cases reverse engineer the formats and write some perl scripts to convert them to BMP. Luckily, they weren't too complex and it was an interesting process, but it also got me thinking too, I've got do wrap all this stuff up now because 10 yrs from now might be too late.
I also notice that USB enclosures do not like old IDE drives. I still have PCs with a PATA interface so that wasn't a big deal.
I was surprised that most of my floppies (hundreds) were fine (~95%)and they weren't well stored.
All my HDDs were good except my 386 laptop which crashed on boot.
So basically I made images of everything. Carbonite for it all, two 16g flashdrives (one offsite) for all the important stuff as well as an external HDD and DVD-R archives every few months. At the moment, I can't see how I can improve on it much.
I have a feeling the current generation of hardware will not hold up as well as the old iron.