jm é1RR¦~yâ6 aõå`U*Ë9 *âLÏLThere are more than one way to handle that scenario. One could very publicly "sunset" (to use his own words) the systems and then lock them down.
https://whatsonchain.com/tx/1ad5a5aa19f1b55991eaab5a2bbe782d8baa454068c8d35e64e8372f84481ec7