The problem with AI is, that it tends to go for the "average" or "middle ground" solution. Also if we start seeing more and more AI movies, the models would learn off other AI generated content and that will degenerate them. It is AI inbreeding.

These things are kind of fundamental to the way machine learning works, because at heart it is statistics.

So either they will generate new movies, that are just reskins of other movies with ever more boring plots. Or they will still need actual writers and actors. Now i know hollywood is doing a lot of the first already. But without actual creativity, bringing along new ideas and starting new franchises, eventually it will get boring even for the most diehard marvel fan.