I work in the email space; thanks to this guy's invention, I can feed my family and have a solid financial life. It is amazing, the web of events, that shape our lives and the lives of others. RIP.
I wonder how much the economy would break down, and have to change, if email suddenly went away?
And even if someone doesn't use it that much for personal communication, it's part of the underlying net infrastructure (think account-creation verification emails, password reset emails, bank statements, etc).
Or suddenly went proprietary.
It might even happen.
Consider what would have happened if email was a patented, proprietary tech (like Twitter, Facebook, etc.) rather than open.