Obviously you two know it all. However I'm sitting in Airbus genfam @ DFW. The Airbus reps and instructors have said Airbus will get the airplane back. We'll get a " fresh airplane" at that point. Hey what do I know.....
That could be the result because by the time the first AA A319/A321 needs a heavy C check, the Airbus Neos will be flying, and if their fuel efficiency improvements are substantial, Airbus can probably sell the used plane to Delta and lease AA a new Neo version with better fuel economy.