GMR (RIP) is essentially a big warehouse with backstage access for all of the big stuff. Spaceship Earth is another case entirely, since when it was built, they had to load all of the show scenes into the top before it was enclosed. It doesn't have any easily-accessible entrance or exit for the movement of elements. Whatever they remove, they're going to have to take out through one of the entrances normally used for guests. They'll probably do most of that during times when the park is closed. The fact that it is so difficult to get things in and out of is likely its saving grace at this point, though. It would be incredibly difficult to tear out the existing ride layout and construct anything totally new inside of it, thank the Phoenicians.
