USB-C ports will replace all other ports and will support protocols like USB 3.1, Thunderbolt 3, DisplayPort, etc while being able to provide power at 5-20 Volt up to 100 Watt.
To use legacy devices one needs an USB-C to USB-A, mini USB, micro USB, Thunderbolt, DisplayPort, etc cable or adapter to make the physical connection.
In the end we just use USB-C to USB-C cables for everything you want to hook up to the PC / Mac and the onboard chips will figure out which protocol to use, if the device needs power or can deliver power, etc, etc.
Maybe the attached pic will explain a few things
