Keynotes

Keynotes should be asynchronous.

A keynote is a speech, right? Speeches are meant, not to be particularly informative anymore, but to transfer Emotional content. Information can be found online or in a book, or in some other more stable and straightforward manner.
He's saying the same things I'm about to write about, so I'll use his example. "How many people are actually paying attention 100%?" A few of us raise our hands. A very few. His point is that no one pays attention in classes anymore. I agree, but not with his reasoning. Or maybe I don't understand his reasoning. He says basically that we're not engaged, so we're not engaged. Away from roundabout arguments.
Speeches should be made for the purpose of moving people. If that is not the point of your keynote address, then put it up online somewhere, or make a video, or Something Else. Don't make us sit through it. Face to face time should be used to better effect than listening to someone ramble on about things that may or may not be relevant, that are probably not all that useful, and that we could almost certainly get a better idea of more quickly if it was in some other format.