It would be perfect if Ashoka survives the dark side temptation, if not the tremendous effort of lucasfilm for changing her appearence would be wasted.
There are signs that Jedi will face more than one sith on this season, that is
if Savage Opress is not a full dark lord, he could be a chief of the sith assassins.
The dark sisters (sith witches) should have to fight in a lightsaber duel, at least at once with several Jedi (Ki Adi Mundi, Shaak Ti, Luminara, Plo Koon, etc)
I wonder, not assuming, that this Season 3 would reveal the interaction of several categories of the Sith hierarchy: acolytes, assasins, commandos, witches, etc), this fact will force Sidious to appear more on screen than previous seasons to define the ranks of those newcoming characters.