"The facts are that [Firefox users] will get more ads, not less, and those ads will not be tailored to their interests," he said. "They'll see untargeted ads, which will look like spam.""

If this is truly the case then Firefox users will notice and either turn the third party cookies back on or complain/switch to chrome. If the effect is that big, and people want to see the targeted ads, what do the ad networks stand to lose?

Firefox is making a right move, there is now a distinctive conscious choice you can make: Firefox, privacy by default. Chrome and IE can never counter that (because of their affiliations with ad networks). Maybe its not the biggest reason to use a browser, but it's a big one and it enforces Firefox's position in the market.