@jayplayco
My ideas to that solution.
1. Agree that Email could be a weak point, but it was one of the things that came into my mind that could still be used in 20 years.
2. loss of email or provider gone -> one of the reasons that the wallet that send the BTC into the future still can change the email address before due date.
3. More BTC -> Just send another amount to the wished timeframe would be the easiest solution here in my opinion. :)