Well, based on the size of the Soarin building in California Adventure it would fit into that picture Joe showed us. ( I was a dork with google Earth and measured. Not that it means anything but it gave a general idea of the sizes.) Actually, the building would have room to "breath" as that piece of real estate is a little larger than the show building.
Now the piece of real estate that REALLY interests me is that piece of land from the Tower of Terror all the way down to the bus parking lot. Granted the buses park there but I don't think it would take much to move that somewhere else on property it's only about blocks 3 of parking. Yes, I know, there's a road there but a indoor queue could go right over that and bam! You've got room for a massive E-Ticket...perhaps even a land.
P.S. It looks like Disney Sea is a little tight for new big attraction locations *inside the park* so I think this is a great site for future expansion aside from the NW corner.
HAVE FUN! =)