AA won't merge with anybody. They'l code-share out the wazzoo, and if they get scope relief or break the APA, they'll expand sub-110 seat flying as outsourced flying, either through Eagle or through a third party.
If they spin Eagle, anything could happen. They'd wind up code sharing US as we buy bigger airplanes and supposedly "Go it alone". (Yeah, right.)
AA's not dancing to the same music as everybody else. Very different culture, really, and after the shenanigans with Reno Air and TWA, a list integration is the last thing anybody wants.
Sidenote: Today in the DFW crew room, there was cake! Why? One of our Captains was celebrating his 30TH ANNIVERSARY WITH EAGLE.
I kid you not.