Well the basic reason for Google's huge success (aside from that little search engine part), is all the money their text ads make. Because the Google ads scan the pages and determine the best ads to show, it kind of killed the concept of banner ads.
On high-traffic sites, or sites with certain types of content, dynamic ads like those from Google may actually not work as well as plain old banner ads. For example, on CNN.com or another news site, dynamic ads may not work well because:
a) the content is a depressing, news story about war and death and an inappropriate ad may show up
b) too much different content is on the page for the robot to figure out the best type of ad to show
The normal, plain old vanilla "banner ad" type business is still huge business - just like print magazine ad marketing, the marketing business will adjust to new technology but in essence it always boils down to showing the consumer and image, and inspiring them to take interest in the ideas behind the image.
40 years in the future when we're all surfing the internet directly with our brains, I think the concept of 'banner ads' will still be around: a big, blatant advertisement, except then it will be literally 'in your face'..

BTW, we just launched our own affiliate program, complete with some banner ads in various sizes, as well as search input boxes. You earn 10% commission for referrals, even if you don't sell art on the site.. have a peek:
http://www.zymmetrical.com/Info/Affiliates/tabid/1449/Default.aspx