New functionality: Now it is possible to have private chats and also Channels. This can replace Slack. But who can make a new channel, and how? I would also prefer to link to a channel in a topic within a discussion in one of the categories to be able to sort of jump out to a channel chat from a topic, and keep it within that topic as a link.
Person-to-Person ‘private’ chats are able to be created by anyone who is Trust Level 1 and above (this will be most users) - @trust_level_1 and subsequent trust levels are an inbuilt anti-spam mechanism which Discourse has and they are auto-incremented according to various criteria.