Now none of the press says she was fired, but when was the last time you saw news about a show getting renewed and literally in the next breath saying the showrunner had decided to depart. People don't decide to depart from TV shows that get renewed. They get pushed. Deadline says she is "stepping down." The Deadline story also says they became concerned with the "creative direction" and that it has become "soapy." Meanwhile, it is the network's highest rated show with adults 18-49.
Whatever the shit that goes on behind the scenes of a creating a show (which in this show's case probably mirrors the stuff we are seeing onscreen), losing Theresa Rebeck is a big deal. She's got a hot show on Broadway - Seminar. She's got more shows getting ready to come to Broadway. She's one of the top female voices in writing and if you think that we would be seeing the amazing Anjelica Huston on TV without a woman as the creator of this show, I've got a big bridge to sell you cheap.
But it is also a significant loss of a female showrunner and creator which needs to be noted. This is one of the biggest shows on TV today. And it was run by a woman. But she was a woman in a sea of men. There were ten executive producers (and none of these ten were actual writers which is highly unusual in TV) and Theresa was the only woman. I don't think I'm going out on a limb here to say that the powers at NBC are going to replace Theresa with a man.
‘Smash’ Creator Theresa Rebeck To Depart (Deadline)