An interesting idea, but one I'd disagree with almost completely. Email works extremely well for me because I can receive it regardless of my availability, and respond to it when I have time. Your blog post notes that email interactions don't match real life; I agree, but I'd consider that a feature. I can easily solve the "important people" problem by using filters to call attention to email from those people, but I'd only need to do that if I couldn't keep up with email in the first place; currently I can see at a glance who my email comes from, and optionally cherry-pick mails to respond to first. Otherwise, to the extent email becomes more like real-life interactions, it becomes less useful to me.