Your proposal basically sends all email to everyone (encrypted), which avoid the need for a DNS entry.
That model already exists, it's NNTP (a.k.a USENET). This basically sends an email (RFC822 body) to all participating servers in an efficient 'flood fill'. (A usenet post is almost identical to an email body).
So PGP+NNTP gives you the protocol side of what you want today.
The issue will be that "sending all email to everyone" probably won't scale, for NNTP or your system.