More money in being a knowledge engine. The users only ever see Google's own native ads which give them 100% of the ad revenue. The users don't go to those pesky sites that make Google only part of the revenue.
If Google doesn't want users to leave their own site there is little we can do as SEO's and webmasters to encourage them. The only strategy open to us as webmasters is to make sure they don't need Google to find us. I think Google is playing a very dangerous game that could make them lots of money initially but then come back and bite them on the proverbial.