How open/decentralized is the advertisement planed in the future

I would like to know how centralized advertising is planed wit BAT and Brave.

If we assume BAT will work very good and replaces the current system how adds are displayed (completely). No more tracker, no more popups every add runs using BAT.

Who controls what adds will be delivered and for what price.

Or phrased differently, would Brave be the only One (monopol) to decide that an add may be advertised or may not. Even with good intentions, this would be an situation I wouldn’t like. Simmular to “If google does not list you, you do not exist”

its about choices advertisers and users get with diversity in the ecosystem with focus on privacy , and monopoly centralization of some kind is inadvertent fact
just look at uphold a completely functional service yet scaring users at large

https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=8478235