About a year ago my dad suggested that in the future, it will be very common to see virtual actors. That is, there will be actors who exist only as the product of CGI and speech synthesis. Additionally, he believes that very famous actors will be preserved in this way - replications of famous actors will be able to fill in for actors at any age and at any point. We are already beginning to see this, and as the technology begins more advanced I believe it will become more acceptable to replace actors with CGI.
Additionally, we are seeing increasingly promising results with neural networks. For instance, they can already generate weird science fiction scripts. Eventually, computer programs should be able to create movie scripts that are at least of passable quality.
This leads to my prediction: within my lifetime, there will be at least one service on which a user can request a custom film and watch it as easily as users can start movies on Netflix today. That is, they will be able to go to a website and say “I want an action movie starring The Governator, Nicolas Cage, and Hilary Duff in which humans fight alien zombies who invade Poland during World War II.” Essentially, there will be a movie for any possible idea on demand.