With regards to the loophole, here's a post from Reddit's churning thread:
My 3rd Citi AA card was upgraded to WE in late January. I received the WE card and activated it around Feb 3. I applied for my 4th Citi AA card on Feb 8. The welcome letter did not mention the bonus. I just received the card today. The Account Information sheet (to which the card was attached) has the following language: "Our records show that you are not eligible for the bonus offer based on a recent opening or closure of your Citi / AAdvantage Platinum Select Card." The online bonus tracker does not appear at the "Your Miles Summary" page.
From this I conclude that I will not get the bonus on this card. With the scattered reports of Citi shutdowns, I am hesitant to send a secure message to ask for confirmation for fear of alerting anyone to look more closely into my Citi accounts. I also don't think I need much more confirmation.
Citi AA Card summary:
1st Citi AA card: Approved 2/18/15. Received 50k bonus.
2nd Citi AA card: Approved 8/20/15. Received 50k bonus.
3rd Citi AA card: Approved 12/7/15. Received 50k bonus, matched to 60k.
4th Citi AA card: Approved 2/8/16. No bonus attached per multiple sources.
ETA: All cards are still open and none were product changed.
I also came across this:
Here's two data points: wife and I just received our first Citi AA platinum cards (applied on 2/7 and 2/8). Both have the 50k bonus attached (SM confirmed + bumped to 60k) but neither had the 50k bonus language anywhere in our welcome letter / packet. So it's quite possible they have removed it from the welcome letter