Have you tried Discord? It's geared towards gamers but it's got most of the features we needed from Slack.
More info: https://support.discordapp.com/hc/en-us/articles/11500098275...
More info: https://support.discordapp.com/hc/en-us/articles/11500098275...
[0]: https://twitter.com/i/web/status/903663357210841088?lang=en
The non-email world is fragmented. Signal? Facebook? Snapchat? Whatsapp? None have achieved ubiquity and their audience is constantly churning over to the next fad platform. Facebook has the best shot and there's still a huge part of the population that doesn't want their FB life to intersect with their work life.
Email is the lowest common denominator. The fact that "younger generations" (as if every 3 years is a "new generation"?) choose a different platform only reinforces the value of email as the only thing that everyone can agree on.