I think Shaak Ti might appear in Season 3 because im sure I saw a Togruta (it wasn't Ahsoka) in the Season 3 trailer.
I noticed that to. After I watched it once during the finale I went online and watched it again and I thought the same thing. The Togruta was more mature looking because the Leiuku horns were much bigger/ longer. Plus, wasn't she on courascant during this time? I thought she was doing something at this time so maybe we will see her character finally introduced!