I know it's a... stretch, but imagine this: - you can't put billboards in the city - you can't place any images, text, etc. banners anywhere (except for tightly controlled, single-design descriptions of businesses in buildings, decided by each municipality like it's already done in some cities to maintain consistent look of historical town centers) - in general, no publicly visible ads of any kind are allowed - no ads in videos, TV, etc.
Where would ads be? - you can search for ads like you do today, in search engines (preferably opt in), i.e. ads become a catalogue, not a "here I am" attention grabber - gray line (recommendations/suggestions which really are ads would need to be limited/removed as well) to be decided
In general, clear up public space and attention holding spaces from explicit commercial interests as much as possible.
I'd love to live a few years in such a world and see whether value propositions of businesses would start shifting...