europeforvisitors - 2:42 pm on Jul 19, 2006 (gmt 0)

however, publishers will certainly leave, if earnings are going down and other options promise better chances.

But the only publishers who'll leave are those whose earnings are going down because of smart pricing, blocking by advertisers who aren't happy with the quality of the traffic they deliver, etc.

If those publishers flee to Yahoo and MSN, it's likely to be a win-win situation for Google: the overall quality of the AdSense network will improve (making AdSense more attractive to advertisers), and Google's competitors will inherit the publishers who are least likely to deliver results for advertisers.

On the downside, Google will lose revenues from the publishers who leave (even if those revenues have been declining), but Google's quality enhancements on the search side over the past 18 months have shown that it's willing to sacrifice short-term revenues for long-term credibility and performance.