You may see lower number of Google Ads on your webpages but that may not necessarily mean lower Adsense income since the Ads shown on your site will have a higher effective CPM.
I think the basic idea behind this latest tweak is cut the supply lines of Scraper Sites or MFA sites that use Adsense Adwords Arbitrage to make money from junk content.
Some people buy cheap Adwords ads to drive users to a site where they write about topics that are likely to attract high-paying ads. If a reader clicks on cheap ad to come to their site, and then leaves the site by clicking on an expensive ad, the website owner makes money on the difference, minus Google's cut.
Google may be working to send such sites to the dungeons by associating Quality Scores to advertiser's landing pages:
The quality of the ad's landing page now affects the Quality Score that the ad receives -- this score helps to determine the amount an advertiser must bid to appear on your site.The changes are already in works and may bring bad news to sites like 8-topsites.com or digg4it.com who are probably the most famous MFA sites.
The lower the Quality Score, the more "expensive" it is for the advertiser to show up on your site. As a result, you should see fewer ads on your pages which lead to low-quality sites
AdsBlackList has a long list of MFA sites that you may added to your Adsense Filter List to block low paying ads that pay a cent per click and take the visitor away from your site.
Shoemoney talked to someone from the Adwords team and she confirmed that the big changes are purely targeted at the arbitragers - "if your running a landing page and directly linking with your affiliate link or running a scraper with nothing but Yahoo/Google ads then YOUR IN TROUBLE!"
And here are a list of some Google Adsense Tips & Tricks that may help you increase your Adsense income.
Section Targeting is also an important step to get relevant ads on your webpages that generally have a better Click through rate.