With google's privacy snafu's and other mishaps, I could see them getting upset within 5 years.
i'm not sure if a company will ever be able to take on Google in search directly
A far more likely scenario for a major change in this sector would be for social search to eclipse the crawl it and rank it model that is currently dominant.
Would you rather make $ 1 from a $.1 investment or $ 10 k from a $ 2k investment (assuming the former isn't scalable because there are no more users to advertise to)? If there is a non trivial time cost in setting up management, billing etc, you might not even bother with the former.
Also, if total return is small and capped, it may not even be worth the time to calculate ROI.
Problems there would be a) to beat Microsoft and Google at that game, and b) it would turn search into a low-margin commodity. Both make it hare to turn a profit.