Now would it be possible for a hard drive to last 100 years ?
yes.. if you never plugged it in and kept it in a sealed bag.. LOL

no, honestly.. as with anything that has mechanical parts.. in this case a motor and bearings, armature parts.. etc.. they will fail from getting "worn out" ....

I've got a 50 yr old water pump for a 1952 oldsmoblie that still works.. how many more years do you think I can get out of that ? hehehehe... I'll tell ya.. if I don't use it much, I'll get another 50.