The ads may not be announced. If ads can be subtly inserted “organically” through crafted weights then AI companies may try to claim that it isn’t advertising, if it’s even possible to catch them doing this. For instance, advertisers could pay to have their product embedded as the “best” in a category during training. If this is done as a fine-tuning step then it could be re-run later as advertisers and base models change.

Counter-counterpoint: people pay exorbitant amounts of money for cable TV channels that still show ads. Even the premium channels (HBO et al.) implicitly show ads in the form of product placement, which incidentally is exactly how I think chatbots will show ads. Most users won't even consciously realize they're there.

Once the ad people are the ones making decisions because they are bringing in all/most of the money, inevitably it happens.