It would be trivial to insert banner ads, or even "native ads" in the response.
LLMs are probably even better suited for monetisation since they have a better understanding of what people want, so a better ad can be shown that is more likely to be clicked.
Do you think people were losing their shit when ChatGPT went into bing simply because web search gets better/easier? No - people were losing their shit because it meant the ads in search are going to be turbo-charged and so that is why the share prices are surging (GOOG up 40% over last 6 months): more ad revenue from "better" ads shown to users.
People still need products to solve problems. When you ask an AI "I have X problem, what products could I use to resolve it?" that is a natural and ethical time to include advertisers into the equation. The LLM can be trained on product specifications, details, and relevant uses, as well as plug in to a review database. Companies can pay to be included in the results of possible solutions and the AI can use the available information to make specific recommendations based on real data.
Hopefully, the future will completely prune intrusive, non-consensual advertising completely and any companies that inject thoughts into our minds will fail.
For some problems. For many more you don't need a "product" at all but advertising still wants to sell you one.
> that is a natural and ethical time to include advertisers into the equation
Not at all. Ads means showing the product of whoever is paying the most or at least preferring paying products over others. Ad-free suggestions means showing the product best suited for the task. If those two match you are defrauding the advertiser by making them pay to show what you would have shown without ads. If they don't match you are degrading the service for the users.