This item is still in the works, no new details to share yet.
Was hoping that Microsoft actually listened and shut this down... Alas, same old Microsoft.
We acknowledge the customer demand for Private Channels and have been hard at work on it. Private Channels is currently in preview with a select group of customers. We expect to release the feature to the public later this Fall, and will update here when we are starting to roll out to all customers. We appreciate all the feedback you have provided to us on this forum and thank you for your patience.