Just because the ad system doesn’t know anything about you, it does know a LOT about the site you are visiting, and specifically the page you are viewing. It can use a onotlogy/taxonomy service to figure out what is on the page, and then serve ads based on that.

What will be affected by lack of cookies are behaviorial targeting (you looked a car site last month, so show something car related on this site) and ads which are designed to only show once to a individual. (or you show them a story on progressive pages).

What it means to publishers is that if they have crap content, they will get a crap CPM, as they can’t use higher CPM ads on lower quality content.