More important for me is wether forts will be mainly above ground again. I think one of the main reasons for forts being so much underground was the need for them to be seperate cells. In an above ground fort you'd expect to be outside at one moment and inside the other moment, which wasn't really possible if combined with a big dungeon.
I want various attack on forts. Not quest specific or anything, just there will occasionally be a group of bandits sneaking in. If its successful, the fort will stay occupied for a few days before the guards reclaim it.