I get why prefer old but works over new and fancy, but what about new and works? They could trial new technology for five or ten years in parallel with the old before switching gaining both the stability of old and proven and the future-proof-ness of "new and we think it will stick but it might not". The reason why it isn't done this way is probably cost, but at what point will the difficulty of sourcing the old tech and people who know how to use it become the more expensive option?

You can still buy new, still shrinkwrapped, recent production floppy disks and new drives. I'd imagine if you're supplying parts for these, a warehouse with a stack of known-to-work floppy disk drives isn't much of an expense and certainly not difficult.

Even if it became a problem, you reasonably have the margins to ask a manufacturer to setup an assembly line and run a new batch just for you - the only downside is that you're likely spending a lot of warehouse space to house the new parts.

I remember reading a news story ~4 (or more?) years ago that the last manufacturer of floppy disks stopped making them. I’m not surprised to learn there’s still plenty in circulation, but I’m a little confused by “recent production”, unless my memory is just wrong...

If you're spending $30mm+ on an airplane, getting specialized media for it is the least of your worries. Also... floppies work decently well. They're not fast, but they work. It's not like your data transfer speeds will improve with thumb drives either... the hardware doing the reading isn't going to be very fast.

"New and works" is used in aircraft that come off the production line today; just look at the flight deck of an A350. New avionics start out in the iPads of GA pilots, then get that 5 to 10 years proving in the flight decks of business jets, finally making it into the cockpits of jetliners.

I'm fairly confident that newer aircraft are using newer, but works, technology. There's no reason to update the hardware on the 747 to use that technology, though. It'll be expensive to certify and retrofit.

Couldn't you just take any USB stick and only write a 2GB partition?

Yes. Usually it is a FAT/FAT32/NTFS formatting issue.

Although the most annoying issue is usually related to SD cards. Most SD Cards these days are usually "SDHC" or "SDXC" cards and formatting them to a 2GB partition doesn't actually work.