Thinking about ad networks

Banner ad networks have been around for quite awhile. But click through rates went through the floor. So along came Google Adsense. Then affiliate programs aggregated by Commission Junction. Found this good thread musing about what is wrong with today’s ad networks: SitePoint Forums - The future of ad networks. I wonder what the next genaration ad networks will be like? Will it be about coverage? (getting ads on sites without them) Will it be about clickthroughs? Branding? Will the advertisers be the same or different?

I read recentlythat Google made something around $1B on its advertising and paid affiliates $378M of that (I probably got the numbers somewhat wrong) If that is so, Google is taking more than 60% margin. With their high overhead I understand. does it really cost 60% - $600M to run the network?