In December last year American Airlines began shutting down frequent flyer loyalty accounts due to credit card rewards abuse. Despite the fact that these American Airlines accounts were shut down, the actual Citi cards continued to work and not accrue any miles. Citi is now sending letters out stating that these cards will be closed within 30 days.
It does strike me as a bit odd that there isn’t any sort of apology from Citi or offer to convert these into other credit cards, but that is generally prohibited in the co-branded credit card relationship.