Thanks for the heads up.
I was planning on stopping at either 3 or 4 per year once I found out about the loophole, and after reading that thread, I think I'll just hold steady at the 3 that I currently have. I do plan on closing two of them, but not until they're more than a year old; the lone card I plan on keeping is now my main card for all charges. Once the two are closed, I'll just go back to grabbing a new card every 18 months and following my original pattern.
I don't do any MS, and all charges are my normal shopping, so I hope that Citi doesn't crack down on me.