I had made a post not long ago saying I think Sylvanas will return to being ‘good’ by teaming up with Arthas before the new video.
https://www.youtube.com/watch?v=yjPcJsl3COs
I knew It, I knew It. Just wait and see. It will be an entire team of OG’s. Except everyone had hoped to kill Sylvanas XD
Add a spoiler tag to your title, please, and try not to give details, so that people don’t mouse over and read stuff they may not want to know. 
Noooo Blizzard, whyyyyy?! 
I’m confused cause I don’t recall seeing Arthas in that video at all. What are we talking about?
You know she’s talking to Anduin in that cinematic right?
In the beta there is a placeholder for a cinematic when she is torturing Anduin.
No you just wait. This Is called speculation. When you don’t know the outcome of something for sure. You make predictions. Sometimes you get It right.
Nothing so far. While I’d like OP to be right, I don’t think she is.
Ok, but your OP you talk about things such as Arthas and then link a video with no Arthas and then say,”I KNEW IT.” I guess this is where my confusion lies.
No, I’m saying this Is what I believe will come to be. But also we haven’t been able to play Shadowlands yet.
Ok. Still doesn’t make sense to me in the context of the OP but ok. Hope you’re right, I guess?
It’s not a spoiler if it’s a guess lol.
Fun, try It out sometime. I get joy from trying to predict these.
Since her transformation into a banshee, Sylvanas has NEVER been ‘good’… not in the slightest.
I’m hesitant that they wouldn’t give her a redemption arc. Same with some other characters. But they could also go the absolute opposite way as well.
I have tried it. I speculate about things in the game all the time. It’s just that usually it makes sense to me and your OP is kinda confusing. That’s legit all I’ve said.
Listen to what Sylvanas says In the video.
Tbh it sounds more like a villain monologue
“Death To The Living”… that has been the Forsaken motivation since the beginning. Sylvanas is one twisted elf. Who knows where the writers will take her now but I hope it involves her head firmly impaled on top of a pike. 
I have felt the same way. But considering how they keep using her In like every expansion and she just keeps becoming more like a god. I figure they will not simply get rid of her. They show her as something of immortal and give her the biggest ego complex of any character In the game. Considering she doesn’t seem cowardly like the past villains. From this I derive they wouldn’t just leave her In the end as a head on a pike. But I could be wrong.