I mean, the topic has already been discussed to the death but punishing Sylvanas as she exists now has become completely senseless ever since her character was "fused" with the 100% good Sylvanas. The Sylvanas that is being "punished" now is simply not the Sylvanas that committed the deeds for which she is being punished.
This essentially undermines the entire idea because there can now never be a genuine process of evil Sylvanas being forced to confront the consequences of her actions and suffering through them (which is the concept of punishment).
Evil Sylvanas will never actually be punished (or redeemed) because she got deleted as a character at the end of 8.1 and that is why the story will never have a satisfying conclusion for most people.