The conventional wisdom is that international usage cannot be monetized as well as US traffic and that is certainly true. But with >80% of your potential users outside of the US, I think the web sector needs to start working harder on international monetization.
Even if international traffic could only be monetized 25% as well as US traffic, when your international traffic is 80% of your total traffic, you would make as much money internationally as domestically. So that’s a lot of potential out there to be tapped.
And of course, not every international market is equal when it comes to monetization. Markets like western europe and japan monetize very well today. Emerging markets like the BRIC countries (Brazil, Russia, China, and India) should be big opportunities for monetization this decade. Other markets may be tough for years to come.