[goto11]

You mean some kind of AI which can read and understand a script and then develop a persona with physical appearance, voice, mannerisms, interpretation of emotional state and interactions with other characters etc.?

I guess such an AI would also be able to write and direct the movie.

[krapp]

Realistically there would be a pipeline with various companies and AIs involved, each specializing in a specific aspect of virtualizion (the way effects houses work today,) not a single AI doing everything.

But yes, everything you mention up to and including writing and directing can and will be automated to the fullest degree possible in time.