I'm having a hard time buying it... "We still sift through an ever-growing list of emails that generally have very low information density." followed by a mock up screenshot with extremely low information density, much much worse than email.

Worse, by stripping email of everything familiar, whatever benefit is introduced by this new system of parsing my email has to be so great/unfathomably grand that I am willing to give up decades of muscle/brain memory, familiarity and trust with how an email system works, compatibility with all other services, ... I could go on.

There's obviously a very difficult problem with email being overwhelming, but I don't see a great difference between the mockup/info on the site and what big companies are doing right now (inbox categorization). If someone wants something different than email, there's always hey.com which is run by a company that has a long reputation for not shutting down services people are using (they still support Basecamp 1.0 and I know people using it, they still support BackPackIt from the early 2000s...)