I delivered an opening keynote earlier this week, probably my 10th. Fully agree with the comments in the article, especially the comment about the application of a story arc. I believe the keynote should set a tone that the can serve as compliment or contrast to the talks and panels for the rest of the conference. I'd rather set forth a unique framework or lens for viewing the rest of the day/week vs. the presentation of a completely new set of data points or theory. Importantly, the keynote should get the audience fired up about the oncoming day's events. Its a unique opportunity to inspire.