At this point of the story and with all the forshadowing and hints. It is almost set in stone that the final raid of the expansion shall be taking place in Stormwind. More so likley as an invasion from the sea. While everyone else is distracted with protecting Thunderbluff. You might ask yourself right now. With what army and what fleet does she want to take stormwind in the first place? Let me explain.
Sylvanas made a pact with Helya in legion. I can see it happen that she aids sylvanas for the invasion. Her Kvaldir and the Naglfar are strong enough to bypass the stormwind harbor defenses and lay a siege to it.
The remaining loyalist forces join in composing of mag’har, forsaken and goblins.
I say with all of these in the equation, we can form a force great enough, to actually take the shining white city of humanity and end the war. As it should be. Rastakhan will be pleased in afterlife with the one ordered his death held hostage. Known as King Anduin Wrynn.
I think blizzard gave is the best hint in before the storm. Not Thunderbluff will burn. But Stormwind.