It's late 2015 for a single reservation system. My assumption that it's the single reservation system that is relevant for elite benefits and the like, not the single operating certificate. See
AA's timeline:
Some benefits, like elite upgrades, will vary by airline until we combine reservation systems at the end of 2015
(I'm actually surprised to hear that a single operating certificate is on track to happen before a single reservation system; I didn't know that was possible.)