Kristin from E! answered the question " Where Has Naomi Been in Private Practice and When is She Coming Back?":
Storyline-wise, Naomi has been overseas tending to William's estate and foundation. In real life, Shonda Rhimes tweeted that Audra McDonald is "taking a break to be a mom. She'll be back."
In fact, Naomi returns next Thursday, Dec. 2, just in time for Addison to decide she wants a baby with Sam. Oh, and Addison is barren, as you may recall. Naomi is a fertility specialist. So...will Addison ask Naomi for help having a baby with Naomi's ex-husband Sam? Say it with me now: Awwwkward!