Do you want to stick with AA or go to another airline? Your banked miles remain banked regardless of your credit card status (as long as they don't expire). You will not get a bonus from switching from one Citi AA card to another. You need to do a new application to get the bonus.

Citi has personal Platinum and Gold AA Cards along with a Platinum Business that earn up to 50K per application. You could also go with Amex Membership Rewards or SPG that allow transfers to AA.

If you want to preserve the credit line, go to citicards.com and pick out a no annual fee card, then call to ask if you can downgrade to it - just don't expect any bonuses.