There’ll probably be no more diskette makers in the future, so the train operator should stop using diskettes. I did a quick googling.
In January 2024, Japan announced it will no longer require floppy-disk copies of government submissions.
I did a quick search on amazon.com too. You can buy diskettes there.
I’m assuming the folks doing the upgrade know what they’re doing. Train operation is key, so to be sure, they may need to slowly move away from diskettes and slowly integrate ssds or whatever the replacement will be.