I think Anduin left at the end of their short cutscene together to explore his own mind. Sylvanas said her goodbyes at the end. The question is how did Sylvanas unite these two factions? Not through heroism but because she was viewed as the dangerous villain by everyone, so even her own people turned against her.
From a player’s perspective - yes, it’s great that her arc did that. But I don’t think characters would view this as a good thing.
Even outcasts can have an important job. And I hope she stays one. Some consequences from her actions should still show.