I don’t think email is as decentralized and federated as it used to be. In theory, email is a service that is simple enough for anyone to run themselves. Most Linux distros come with sendmail, so theoretically it should be as easy as reading the manual and exposing some ports. Spam is performed server side both at the origin and at the destination to mitigate bad actors, and because email is simple, there should be n…
Apart from that, email is not going anywhere (not going away) anytime soon as the standard medium for B2B communication. And in B2C communication as well, an email address is the one baseline you can count on everyone having. I don't see that being replaced by anything proprietary either.