Do you think HTML5 has an effect on SEO? specially the <content> tag and the <aside> tag? You think robots will prioritize the content of your site if it's in <content> tag? and it will get the main topic on <header> tag?
I am not sure about the tag that you are talking about, however still if we consider the effect of HTML5 on SEO then I think there must be some changes to be made in SEO techniques. I can't predict which but I too think that search engines will make some changes in the algorithms which, thus, require relevant changes in SEO.