Demanding evidence for predictions like this is a bit... hm. Arrogant, maybe. A prediction is a commitment. We want people to make predictions. The evidence we get when those predictions come true or not. Would you be willing to make the opposite prediction?
I don’t have any evidence that you will, but since you seem to think that’s ok, here goes!
The complement of the claim is essentially "food manufacturers will never again attempt to modify their recipes to make them more hyperpalatable, now that GLP-1 exists." Does that need evidence? It's the null hypothesis, but it certainly sounds a lot more unrealistic than the opposite.
Designing a food to be more appealing is also a relatively well understood process that is already carried out, but Ozempic seems to blunt the effectiveness of it.
Food companies will surely try to make food that is appealing for Ozempic users, and will do so if they can. But it is a massive assumption that they will be able to, given that they're already doing as much as possible to make food appealing to people.
So there is significant uncertainty that the food companies can do what the parent suggested they would do.