Very interesting @Doug Den Hoed - AtAppStore. Teams is an impressive product‚. With the ability for users to not only communicate and collaborate but also use Power BI reports and PowerApps within Teams, it could become the single app that many business users use for their daily work (if their organisation is already onboard with the 'Power Platform').
As suggested in the video, Slack probably needs to become part of another platform of products that appeal to organisations who are not already on the Office 365 / Power Platform train.