James at 2010-01-19 16:39:19:
For me, the main job of the protagonist is to drive the story. It's their actions that cause the dominos of the story to fall.
A protagonist can change, many times does change, but doesn't always HAVE to be the one that changes.
How does Indiana Jones change? I suppose he learns to love, maybe? Maybe he learns not to look into the ark, learning that somethings really are sacred, and should be left alone (although in the end he's angry that the ark gets locked away, so not sure there's really been a lesson learned there?)
I'd suggest that Ferris is still the protagonist: he's challenged numerous times to change, he forces the action that drives the movie, but sticks to his beliefs, come hell or high water, and in the process helps his friend Cameron grow and change.
Sometimes it's the antagonist who changes, and it's the protagonist's strength of mind (and his refusal to change) that forces that change!
As long as someone changes/grows because of the events of the movie, it will still be a successful story. It just doesn't have to always be the protag.