FWIW, the long term plan is apparently to close the Nest and move the regionals to terminal 5. Supposedly this won't/can't happen until, at the earliest, stage 1 of the midfield terminal is completed (2020), but maybe not until the big terminal 2/3 remodel/expansion is completed or perhaps not until (the as yet unapproved/unfunded) stage 2 of the midfield terminal is completed (2025?, 2030?).
In the meantime, I wouldn't expect AA to make any significant investments in the Nest as it's a dead man walking in their eyes.