they won't launch Adsense killer. Don't have stats with me, but seen it yesterday that CPM clickthrough Google vs Fb is 2:1. AdSense is very well positioned since ever. I don't think you could convince an average website owner to switch to FB Ads for 50% less in profits.

That's not really a fair assessment. When people are on facebook they are there to be on facebook. When people are on google they are specifically looking to go somewhere else. Of course they are going to have a higher click-through.

When you are talking about another website, we get to a middle ground that might be looking for something specific and might just be browsing. Having all of facebooks data about someone and giving them targeted ads could very well work better than google at that point on the spectrum.

I'm not saying it will be better, but it's certainly possible, and comparing google's clicks to facebook is comparing apples to oranges. As someone who has several websites using adsense I would certainly be willing to give facebook a trial run and do some A/B testing.

OK, I see your point. But still the question remains if FB could convince popular websites to try Ads with them. It would definitely be an interesting to see the results.

Yeah keep in mind that the really popular websites don't use adsense. They sell their own advertising space for more than they can make using adsense. Most website owners like to a/b test all kinds of things though. I've tried lots of different ways of monetizing mine and have ended up back at adsense because it's been the best for me. Given that, I would definitely test facebook to see how it did and if it did better i'd keep it, if not I'd go back to adsense.