Anyone who's played Cyberpunk 2077 might remember the big ads projected into the sky above the city. It adds a really cool dystopian atmosphere to the game.
It's not theoretical, look up Candy Crush New York.
They can start going all out with regular ad programming over tier 1 cities many times each day almost as soon as they find themselves able to get away with it.
It's will be regular within a few years if we let it.