My wife and I were talking about this not too long ago. I feel like GMR could definitely use an update, although I am not sure what all I would cut, other than probably Tarzan, Footlight Parade, and the horror section. We were trying to go through movies that have been released since the attraction was built, that would fit the idea of being a true Hollywood classic. The movies wouldn't have to be too old, considering Raiders of the Lost Ark was like seven years old when the attraction premiered (even though it does stand the test of time).
I would say no to Star Wars (even thought it is older than the attraction and a true classic), since it has Star Tours and is likely getting an expanded area. If Indiana Jones is also expanded (with a coaster or dark ride), I guess I would be ok with them losing that. Also, no to Pirates of the Caribbean, considering it's already a major attraction, so we don't need a ride based on a movie based on a ride.
A few movies, both new and old, that I think qualify...
Lord of the Rings: This is the most obvious one, and I know there have been rumors of both Disney and Universal making a play at the license, but I doubt it'll ever happen at Disney, unfortunately.
Titanic: I know a lot of people would be against this because it's "cool" to hate this movie for some reason, but it's one of the biggest movies of all time and was directed by the man who did the OTHER biggest movie of all time and currently has a working relationship with Walt Disney World. Several scenes from the movie would work well for the attraction.
Gone With The Wind: This just needs to be there. I'm surprised it's not already in the ride itself, as opposed to just the video package.
This last one, I know I'm probably alone here, but this movie like immediately came to my mind when thinking of this. It's one of the most beloved children's films of all time and has many scenes that would lend themselves well to the attraction. It's my favorite movie of all time, and I still watch it regularly at the age of 30... The Goonies.