Will Google AdWords take all the profit from e-commerce?

Learning how to advertise in AdWords I noticed that there are some keywords that are a lot more expensive than others. For example, to reach the top position for “auto insurance” you will have to pay around $26.24 per click. On the other hand, for “bicycles” or “LCD screens” you pay less than $5 per click. This is consistent with the competition for advertisement that you see on Google. When you search “auto insurance” you get the maximum amount of ads (3 on top, and 8 on the right side). When you search for “bicycles” you get no top ads and only 3 ads on the right side. In the extreme, if you search “nasa” you get no ads whatsoever.
This is due mainly to two things. First, the characteristics of the keyword people use to get to the product or service. For example, how broad or narrow is the keyword (e.g. a particular product reference vs. “clothes”). Keywords that unambiguously express and intent to buy (e.g. “auto insurance”) are more expensive than broader terms that might express different intents. I would expect narrow keywords to have a higher click through rate than broader terms and thus be more expensive. Second, the characteristics of the industry, in particular if consumers tend to buy the product or service on-line, drive prices of on-line advertisement. In industries like insurance where customers don’t switch as much as in other services, and where customers can get quotes on-line, there is huge competition for customer acquisition.
Google’s preeminent position as the top search engine in most of the world, coupled with its auction based pricing for advertisement, allows Google to extract almost all the profit of an additional customer acquired on-line. This is particularly true in industries where on-line purchases account for a significant part of revenues. I look forward to seeing how companies respond in the future to avoid depending significantly on their position on Google.