I agree, I don't think we should mislead or trap users, but rather accustom them to boxes of information which are there for curiosity, "related" stuff (graphic

I agree, I don't think we should mislead or trap users, but rather accustom them to boxes of information which are there for curiosity, "related" stuff (graphically different : smaller grayish text?), or at least some kind of placeholder (a grey box will do). Those should definitely not be involved in any workflow of the service. My point is just to soften the transition, by preparing some ads areas so that they don't appear one day, stealing space from the app.