I disagree. This is great for Slack. They already have a product that people love, and of course this will raise their profile immeasurably, as people hear abou

I disagree. This is great for Slack. They already have a product that people love, and of course this will raise their profile immeasurably, as people hear about FB's play and look into the available options. Additionally, Slack now has just about the best tagline in the world: 'We're not Facebook'.