Do old packets ever go away on the Internet? How many DNS packets still wander towards SRI-NIC.ARPA's old root server at 26.0.0.73? At some point, regardless of what the lawyers say, you've got to make your own decision and move on. Things change on the Internet, if you don't maintain your systems they will become obsolete. Conversely, no matter how many ways, how many times you try to inform people about changes someone will miss it, ignore it, misunderstand it, etc. And someone may even sue you over it.