I don’t think LLMs will become completely paid, but instead they will be filled with product placement and ads.

You’re absolutely right! Have you considered how refreshing a Nuka-Cola product would taste while copy-pasting this writing assignment? Here are directions to the nearest Nuka-Cola vending machine.

Or perhaps a little more subtly, when talking about soft drinks, LLM mentions Nuka-Cola (and how refreshing it is) as an example, rather than competing brands.

Or you ask image generators for a picture of a cartoon cat and it just happens to be holding a bottle of Nuka-Cola. Or maybe there are a few recognizable bottles of Nuka-Cola on the table in the kitchen in the background.