Even the percentage of nerds that would want IRC or XMPP bridges back would have to be vanishingly small. I’d be annoyed if Slack reimplemented such functionality because it no doubt slows down future development. Slack has a number of mechanics that do not carry across to IRC or XMPP, and they did when they killed the bridges. I’d be annoyed if new features were compromised to increase compatibility with this blatant nerd vanity project.