Microsoft have enabled a preview option in Outlook for the new shared calendar functionality. Have a look at this video for an overview.
Microsoft is continuing to invest in Outlook for Windows calendar capabilities to assist customers in managing their time and connecting with people who help them achieve more. We are introducing an opportunity for Office 365 customers to preview new shared calendar capabilities aimed at improving the speed and reliability of how they sync. Learn more at the Outlook Help Center: https://support.office.com/outlook