Nothing is for sure yet, but I also would think, that the most logical step for her is to put 2 3-3 combinations, or some other types of combination like 3-2-2. However Brian must know better. What I'm sure about is that if she will try to learn 3A they won't push it too hard, because Yuna's health is the top priority for them, so there is nothing to worry about...
She's done 3-2-2 most of her career. She can do them easily she just does the 2axel/2toe/2loop because she switched to the 3lutz/3toe. The thing is that 2 3/3s in the long won't change her base value, so its not worth it.