Here is another example of a company taking a percentage of sales instead of a fixed fee for their work. This will definitely become more common in the future. There is an upfront loss of income, but the potential upside is very big.
There is also a lot of great information on advanced SEO techniques in the video. For many companies, just fixing technical problems and correctly siloing your content into categories will have a major impact on search traffic. There is some solid advice here.