You can already get a hacked up public chat via Slack. There's a package (which is all set to run on Heroku) that automates the process of sending an invite to the Slack organization so that anyone on the public web can do it.
I noticed this when the Bootstrap 4.0a announcement had a link inviting you to join their Slack:
> For those jamming on v4 with us, we also have a dedicated v4 Slack channel. Jump in to talk shop and work with your fellow Bootstrappers. If you haven’t yet, join our official Slack room![0].
[0] https://bootstrap-slack.herokuapp.com/