The great advertising slowdown has already begun with the coming death of dozens and dozens of web-ad brokers.
Online ad networks, which started to emerge about a decade ago, offer marketers a one-stop shop to buy ads across dozens, or even hundreds, of websites. Most networks either pay a website upfront for the site's advertising inventory and keep the revenue on the ads they sell, or split their ad revenues with the site. Which works until it doesn't. And the fallout isn't limited to the small players.