I disassociated with a letter that asked that I be informed when and if an announcement is made about me. I was never informed or contacted. I later sent a certified letter to the congregation asking about my status. I didn't receive a reply. I then sent a letter to the headquarters. They replied. They told me to contact the local congregation.
My letter made some legal threats so I think its possible that they never made an announcement about me. However, I did send other letters to friends and relatives, so I'm still shunned.
The one upside is that if I run across a JW who doesn't know about my situation, I don't feel any obligation to tell them that an announcement has been made, because I honestly don't know if there has been one.
In theory, in the USA, they can't decide to make an announcement later if they decide not to make an announcement when the resignation happens. They can inform the congregation when someone leaves, but making an anouncement a long time after the fact could be viewed as punishing a nonmember and might not be tolerated. The Mormons have gotten into legal trouble for doing things like that. It makes me wonder if an appropriately worded DA letter with legal threats could could prevent an immediate announcement from being made and legally prevent them from taking any future action.