You don't expect the watch to hang around forever, either. You'll lose it, sell it, or it will break. We don't want a future with indestructible watches littering the streets.
For memorials, it could be as uniform as firstname.lastname.disambiguation.birthyear.deathyear with the requirement that each person could only register one domain under the birthyear.deathyear root.
To get around the problem of a numeric TLD, I suggest using Roman numerals (and telling Myanmar it has to go back to using .bu).