As per the latest rumor, the accessory that is codenamed “Munchkin” will have three USB ports, one HDMI and one DisplayPort. Your phone can also be charged while plugged into the dock. The accessory will provide a way to use continuum for the displays that don’t support Miracast.
Continuum for phones lets one use Windows 10 Mobile running smartphones with supported hardware like a full PC on supported display. Read our coverage of continuum for phones here.