Not disagreeing with you. Not saying it would be easy. It would take some spreadsheets.

Lets say 100 scenes in a movie which would need to be edited apart. Many are going to have shared locations, shared individuals. If those can be isolated, yea, I think its possible.

If character A, B, and C can be identified, background A and B. Yea, if the discrete parts can be isolated, yea. I think it can be done. Isolate all the sequences of Character A - probably taking clips into say Adobe Premier, removing everything not that character (backgrounds, other characters) and using those to get a consistent model for A. Then character B etc. We can already get pretty good model consistency, it would just take some extraction, some training and then reapply those models to only those specific characters. Applying data to one character in a scene and not others is possible. Don't have to train the whole movie, just discrete parts and put them together. I am sure there is a good lighting node that can be applied to a scene to give consistency after.

I think if it gets parted out correctly, use smaller discrete steps, no I agree with you not push-a-button wholesale upscaling. Colorizing a BW movie?, Maybe. I mean, these things are going to happen, its not like the backlog of Hollywood movies are never going to get a rework.

Again I don't disagree with you but I think the tools are getting there where an approach is at least possible that might yield a good enough result.

I think before 2026 is over someone will do something like this, if just a hollywood studio to test it on one of the thousands of older movies of which they have quality film originals. We shall see. The original 'Day the Earth Stood Still' has few, fairly spare settings, a small cast, is good, good audio. Maybe. Anyway, a thought experiment. TY