To all hungry devs who can't wait to build something amazing: don't try to reinvent the wheel, build on top of it. Leave the email be, and focus on what's next.
Just because something WORKS doesn't mean it works WELL. Making an Asynchronous email protocol would not be difficult. We can do it. Everyone talking about re-inventing email is talking about making a protocol, not centralizing it, not de-synchronizing it.
Email is an AWFUL AWFUL mess. It was good for its era but its no longer as good. Any good replacement will use things like MIME and other such things and simply be a better replacement to the protocol. It'll be the same thing but better.
Which has happened many times before, considering how many versions of POP and IMAP there are. Or the fact that IMAP even exists. Somebody said that email was bad and it needed this and they made it, now we all use it.
Clearly, there is room for improvement.
Nothing is beyond disruption. Just because a technology is sufficiently functional doesn't mean there's no benefit to rethinking it.