What does Katniss believe will be the consequences of her actions at the private audition with the Gamemakers?

Answer: Katniss believes that the Gamemakers will arrest her, execute or turn her into an Avox.

Shortly after the thought of what they might do to her, she concludes it doesn't matter anyways since she was not going to win in whichever way.

She is just seen, to the readers, as someone who is anxious as she thinks about her mother and sister.