I just finished having lunch with an old friend (and industry veteran) who is currently in Google's partnership group. She manages larger AdSense publisher relationships such The New York Times, About.com, etc. However, Google makes a significant amount of revenue from mid and smaller AdSense publishers...and vice versa.

To that point, an AdSense affiliate has written a guidebook titled "Make Easy Money with Google : Using the AdSense Advertising Program" on how average folks can make money with Google.

Force your Web site to start earning its keep by using Google to draw more eyes--and wallets--to your content. In this four-color guide from veteran author and Web developer Eric Giguere, you'll learn all about Google's AdSense program and how you can use it to make your Web site more profitable.

Affiliate marketers have not seen a significant slide in affiliates moving to AdSense yet. However, it is widely speculated that successful Google and Yahoo affiliate programs could move traditional affiliates from CPA based relationships direct with advertisers, to CPC based relationships (for the same advertisers maybe) where they work through Google's AdSense.

here is some additional information on this topic from internet stock blog

Quantifying the vulnerability: Google generated 48% of its Q4 revenue from its "partners network". It includes major search partners like Ask Jeeves, AOL and Shopping.com, but it's fair to assume that a significant chunk of that 48% also came from small web publishers. Note also that Google pays a lower proportion of revenues to smaller publishers than to large search and content partners. A disproportionate amount of profit thus comes from AdSense for smaller web publishers.

The lure of CPC opportunities will be very tempting for affiliates. This puts further stress that advertisers must bolster their relationships with key affiliate partners or risk losing them to the lure of Search Affiliate Programs and the CPC.

All my money is on this not having much impact given that its equally widely agreed upon that many affiliates don't produce quality content beyond regurgitated data feeds and coupon sites. Yes, those that do pick up AdSense and other such services.

Yes, coupon sites and forum sites like FatWallet are leveraging AdSense... but they're also expanding relationships with advertisers beyond CPA and/or pure commission on actions.

It's an effective earnings-per-click-world in my opinion and affiliates will go where they can do best - elevating offers (and, in the case of AdSense, services) that produce results and eliminating those that do not. Smart affiliates will expand relationships beyond what affiliate networks can facilitate. eBates has been doing that for years now.