I feel like this will be the entirety of the Forsaken's response if that "Sylvanas is nuts, gotta kill her" expansion people always rave about actually happens someday.
I see this less as Blizzard adding powers to Sylvanas's arsenal and more clarifying that she does have abilities we haven't seen her use yet. Like I said, I've always felt like she should be able to do more as the queen of banshees beyond her usual banshee wail.
Also, isn't she supposed to have all kinds of crazy dark ranger powers we haven't seen her use in WoW either?