We should create something like the olympiad to gather together and re-tell the epic story of danger every few years, rather than building a monument and hoping it still means something on its own.
[0] https://99percentinvisible.org/episode/ten-thousand-years/ [1] https://www.youtube.com/watch?v=g78hZIEqONM
That way we keep this alive in the public consciences and even if the competition dies out, hopefully at least one work will survive 10,000 years.
But, I do think that some active process and culture to guard or maintain a waste pile is probably necessary. So, don't fixate on some naive visitor you have to protect from all harm in the distant future. Settle for minimizing the delay and accumulative harm before new visitors figure it out and become the new keepers of the message.