Man, this is so misguided....
1. Stagecraft/virtual production is a thing, yes, but the backgrounds are not "AI rendered," they're 3D scenes built in Unreal. They have to be, because they need to dynamically react to the camera moving to create parallax.
2. Yes, some people are using AI to plan scenes. With respect to your relative, those people are not the ones getting hired on large projects. When someone is hired in the film industry, they're hired for their specific taste, creative eye, and opinions. That contribution is literally their whole job. Outsourcing that task to AI is, within the industry, seen as an indication that someone is inexperienced or simply bad at their job. Crews don't want to work for those people, and audiences don't want to watch content created that way.
3. It's easy to "expect" that "one day" AI might become the way movies are captured if you don't actually understand the limitations of AI video generation versus the demands of filmmakers and the expectations of audiences. Putting aside the obvious stuff like continuity, shot duration, and resolution...GenAI is not color managed, it's not physically accurate, the results can't be copyrighted and it struggles with anything not in its training data (I.E., genuinely new ideas.)
This is NOT to say that this technology has no future in the film industry, obviously it does. But half the movies at the Oscars last year were shot on film, so the notion that all filmmaking is just going to turn into pixel soup being generated from prompts is just hilarious to everyone actually within the industry.
Who cares about Oscars? It's about sales and mind-share. Ticket sales still have not recovered to pre-COVID levels, and they were already in a severe downward trend before the pandemic.
The trend is that increasingly, the entertainment people consume comes from small-time creators. And these small creators have thus far had very little capacity to create truly visually appealing content and take on more ambitious works. And still, they've been taking mindshare from the movie industry.
Increasingly sophisticated experiences are becoming possible for these creators via AI tools. Where do you think this is going? Keep on laughing it up at your award ceremonies, but the audience is moving on.
The future is probably not 100% generated, but probably a mix of generation + animation + motion capture. AI is not going to be able to replicate the deep and affecting performances you get from humans—I fully believe it can recreate some aspects of the visual arts, but no way is it going to get to the point where it will be the best of the best. It may become good enough, which is a thing and will make an impact, but I think creatives will still want that kind of control.
And when we see the edges of that control, people will be interested in seeing things that make it "the old way," part of the reason you see a lot more practical effects these days, and I would include the background-in-unreal backdrops there, because they read as more real than actors in front of a green screen—for reasons that are totally unconscious unless you are highly trained in the differences.
While I do think gen AI is going to change how movies and TV shows get made, anyone telling you it will be a whole hog replacement has not studied the history of multimedia and probably hasn't made anything that required a high-level of vision themselves.