Make sure you maintain control over the domain and always have a robots.txt file present, because if you ever lose that, those files will become visible again. Good luck arranging for your descendents to do this after you die.
I'm pretty certain that this isn't the case. If anything, it's the other way around - if a domain changes hands, and the new owner sets up a restrictive robots.txt, the content in the archive is made unavailable, and stays unavailable even if the robots.txt (or the whole domain) later disappears.
