My team has many boards which are shared across multiple members, but are rarely used . For example, we have an "Out of Office" board which we only use when someone is away so that we can have coverage of their emails in a structured manner. It would be great to have a toggle to mark the board as "inactive", and have it show up in a collapsed side menu instead. These boards would still be useable, but would not take up excess real-estate in the sidebar. If one of these boards is needed, you would uncheck the "inactive" box, and it would reappear on the regular side menu.