Pessimistic Scenario #4:
You dig up the backup drive, find that it's still in pristine condition. But then you realize that in the intervening years Apple has gained 100% of the computer market and contemporary computers no longer come with USB ports.
If you doubt such a scenario could happen, I can show you shoeboxes full of floppy disks, 8mm tapes, VHS-C tapes and Iomega Zip disks that prove the point.