I immediately thought of Nicole when I saw the casting call. Also, Kyle Lowder, AZ's husband, just got fired from B&B. He has been pursuing his singing career in Italy, so I wonder if they could possibly be moving there or spending a good amount of time there, which may necessitate her leaving the show.
Sami never entered my mind, but it could be her as well, possibly. However, they already work around Ali's schedule and she only works three days now, so I can't see her leaving. She loves the limelight too much.
LOL, it's probably neither, but it's fun to speculate.