Regardless of promotions I don´t think there´s anything microsoft can do at this point. The consolidation of PS4 can´t be easily stopped.
Best chance microsoft has is next year, when they should completely reboot xbox. Still may be a hard sell since Sony will most likely ride on PS4 success for a long time and release hardware "updates".
I wonder if from now on customers will avoid changing platforms the same way phone users do. If that happens, this iterative hardware model couldn´t have happened in a worst time for microsoft.