I work for AA and will venture a guess. Mr. Parker was the first to offer a "flow" program as a legacy major carrier. He believes that a properly constructed "flow" program will attract the necessary talent in the pilot pool without having to resort to a "cash war" for pilots. He has stated so in employee meetings. I believe that the reduction in flying by some contract carriers will allow AA to bring more flying on the "wholly owned", Envoy, Piedmont, & PSA, and increase the flow. Envoy already has direct entry captains.
AA will never bring all regional flying in-house. They will always want some contractors out there to keep a lid on costs. It's just that now with the pilot shortage the most effective way to control pilot costs is with the promise of a flow to mainline. AA management believes that it will reduce the pressure on pilot cost demands at contract time.