I've seen people using very simple sketches as prompts which work ok to get fairly simple compositions that try to match the sketch. I haven't yet seen examples where the inital sketch is more sophisicated and includes things like specific lighting or perspective foreshortening- but you may be right that some hybrid input of human plus AI may evolve in the future- it's an interesting idea.

I'm less convinced on the AGI side. At present AI Art is a kind of trick- it looks impressive but is less than it seems to be because the AI has no actual understanding of the things it is depicting- it deals in patterns of pixels that correlate to word combinations- it has no idea that these patterns represent volumes in 3D space that have surface material qualities that interact with the light sources in the scene.

To be a truly viable substitute for human artists AI would have to move beyond 2D and be able to understand that the scenes it generates are abstractions from a 3 Dimensional reality.

I can at least imagine a sort of autonomous version of Blender or 3D Max that in response to a prompt then builds a complete 3D scene, including geometric objects, textures, materials, light sources and volumetric effects like mist and ariel perspective- and from this render 2D images from any perspective desired.

The thing I find harder to imagine is how such a system could conjure 3D representations of imaginary objects and scenes that do not exist- where would the training data come from to make this possible?