Such an "interactive" use would need to keep the basic structure of email; for example, a bot you can email and it talks back to you. (Such things have been tried before, but never really caught on.)

If Discord had the same spam or mass marketing problems that email and postal mail have, nobody would willingly use Discord. As it stands, the primary purpose of email is to get authentication codes emailed to you so you can login to other things.

This to me is the strongest argument in favor full evolving email into something else. It's damn near pointless, nobody needs digital letters and just like our IRL mailboxes they have become our distal trash bins. I would love to email to work up the stack and lose it's unstructured nature for most use cases.

People use email for 2FA codes and such, why not go the whole way and let email and Google Authenticator be the same thing.