It's large enough to be a pavilion with the ride attached, similar to Soarin'. Don't know if that is the actual plan. You could have pre-show queue, exhibits, and maybe a counter service restaurant similar to Sunshine Seasons.
I think you’re right that they could put all that in there and still have room to spare. I don’t think that’s the plan though which just makes whatever their actual plan is such a mystery.
The current building will be purely queues, preshow, load and unload. With a pre launch show area.
Hard to believe I know.