If you're storing a message for 100 years, and you're considering a one-time pad, just put the plaintext message wherever it is you plan to hide the equally long key for 100 years. "You can use a one-time pad" is a little like saying "you can just not encrypt".
What a one-time pad gives you is the ability to time-shift: You can meet in person now, exchange your one-time pad, and then securely communicate later. (And destroy the pad after you communicated.)
I don't really get the hostility in your response. Yes, one-time pads are not a practical solution for most use cases, but I never claimed they would be. I was just making a point about their "theoretically unbreakable" property, which I thought is interesting in this context.
