I've heard that the San Fran buildings, including the Disaster queue buildings, are staying. The actual show building backstage will be leveled.
Teebin, I'm thinking you and I have heard the same things. The only thing noted to me that you haven't said is that the load/unload will be similar to Disaster's current setup.
Based on that, I'm expecting the warehouse entrance near Beetlejuice, warehouse queue a newly constructed area, and Disaster's preshow area to be reused for the rave scene.