There's no possible way that this could be implemented. Think about it, there are almost 100,000 congregations worldwide. The society would have to think of 100,000 ways to say the same thing in their letters to the bodies of elders worldwide in order to have each letter be distinct. How many man hours would that require? And they would have to do the same thing for every single letter that gets sent out.
Even if the society decided to follow through with this, how would you determine which elder leaked the information? Couldn't the elders simply deny having done it or claim that the letter was stolen from the congregation archives. The foul odor coming from that rumor is suffocating. I wouldn't pay any attention to it.
No, it's not that complicated. The content of the letter could be the same; it could just be the secretary:author initials that are different (i.e., "KBG:CIA" at the top). That being said, I think it's more likely that somebody that DOESN'T WANT letters to BOE posted (a CO, DO, or even the WTS themselves) that posted the initial item in this thread, masquerading as a "tip", but with information that will obviously NOT be implemented, for logistic reasons, just to "scare" anybody that HAS been leaking info into thinking "maybe I better stop or I'll get caught". No actual changes implemented, mission accomplished. Except that there will still be those that "don't care!" and will post the letters anyhow... So, long and short of it, I don't think the Society is really going to do this. If they ARE, if the information is genuine, then there really is some cult paranoia going on at Brooklyn. As somebody else said, they obviously don't trust Jehovah or the Holy Spirit to deal with it in due season.