This is old but an FYI
AA 176 on 1/2/18 was canceled due to maintenance. It looked like the incoming AA175 was canceled.
Looks like people on affected flights were put on AA60 (later NRT-DFW flight) or rerouted through ORD and LAX or HND-LAX. Interestingly, it seemed the NRT-:LAX flight might have been a 77W based on the seat map in expert flyer.