> And if we had a new spec for irc, would we need Slack/Discord/MS Teams/etc? They could then all talk to each other. We shouldn't be trying to reinvent the wheel, we should be using these older services in our platforms.

The reason we have all those separate systems is not that there are no alternatives: irc could have evolved with a new spec, but there is also XMPP (Jabber)... The reason is that all those systems like Slack/Discord/MS Teams do not interoperate with each other is that they are developed by companies that need to make money, and they want to force and keep users on their systems.

I think email is the only communication protocol that is still very popular and works across providers. I don't think it will disappear anytime soon. At this point, email providers cannot lock their users into their own system: no one can imagine that you'd be only able to email other gmail accounts from a gmail account or other microsoft accounts from a microsoft account.