Some speculations about the ending of Battle Escape:
It's been confirmed that the huge cylindrical structure is the unload hall:
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Now, recall a year ago when a notable thing about the Battle Escape building was the huge pit dug in the ground. They would later place an hourglass-shaped bridge across this pit: (screencap from ShesInLosAngeles video; pit outlined in red, bridge outlined in blue.)
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Notice that, layout-wise, the unload hall is right outside of where the pit and bridge are in the building. So I speculate that the pit room probably contains the finale scene.
As evidence, in this DHS image from Bioreconstruct, I've highlighted a vehicle-sized opening, lining up exactly with where the bridge is within the pit room, and exactly where the cylindrical structure will be built at DHS:
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The portal shown above would be the passage for vehicles to exit the show building into the unload area.
And then, from the recent Disneyland aerial, notice how there appears to be another opening on the corner of the building. This is likely the passage for the vehicles to return into the building after the passengers disembark:
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I imagine that in the unload area, we're going to see a kind of 'reverse' version of the entrance illusion from the queue. (The entrance where it seems we enter a space ship but secretly enter the rotating space travel scene within the show building.) So basically I imagine that, for unload, the ride vehicles will emerge from some kind of 'wreckage' within the cylinder that covers up the portal into the show building.
As for the finale scene itself, looking at the structure, my guess would be that the room contains two dome screens which will depict a crashing return journey to Galaxy's Edge. (Since the start of the experience involves us leaving the planet, we have to return somehow.) I can't find the aerial image where it was visible, but there seemed to be a curved steel framework that spanned the full height of the pit room, which would be the support of a screen. I think the function of the bridge/pit is to help add height so the screen encompasses the rider's full field of view, such as with Soarin.
Plus, the way the bridge is angled inward could hint that it's designed to position the vehicles inward to face the screen, and the fact that there is a second floor of the same shape above the bridge could hint that the upper floors are for projection hardware: (screencap from ShesInLosAngeles video)
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This would also make sense if the trackless vehicles move in batches of 4. So I think the ending will work something like this:
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To be honest I slightly hope that I'm wrong and that the finale is something more than just a screen, but this is my guess of what it is.