Once you get past the major names and into the scroll, the text usually moves from the bottom of the screen upwards. This works naturally with the way we read English. But I've seen at least one movie do it in reverse with the text moving downwards. I thought it was the original 'Repo Man' but the only instance of those end credits I can find on YouTube seems to indicate that's not it.
Whatever movie did it, it makes me wonder if the screen could simply be split in two, with major credits scrolling upwards on the left half and more minor roles scrolling downwards on the right half, perhaps at a different speed. Major stars, directors, producers, etc. would still get their full screen credits before the scrolling started. Deciding who ends up on with side of the screen would of course be another complication.
I just checked my copy of the Criterion Collection version of Repo Man and the credits do go in reverse, moving downward. (I also saw it not too long ago in a theater and remembered it going in reverse, for what that's worth.)
Whatever movie did it, it makes me wonder if the screen could simply be split in two, with major credits scrolling upwards on the left half and more minor roles scrolling downwards on the right half, perhaps at a different speed. Major stars, directors, producers, etc. would still get their full screen credits before the scrolling started. Deciding who ends up on with side of the screen would of course be another complication.