USB-C isn’t the thing that needs to change to get there: it’s Windows, and possibly mainboard firmware.
When you connect two Macs together through FireWire, Thunderbolt or USB-C, they’ll handshake and create a happy little ad-hoc network. Apps like Migration Assistant will be able to create a proper link between two Macs that allow users, settings, apps and documents to be imported form one machine to the next. Great for setting up a new Mac, and picking up right where you left off on the old one. These are all software features.
Not quite like...
It’s similar (but quite superior) to the ‘Easy Transfer’ feature that was introduced in Windows Vista and then mostly forgotten, though that feature required a special USB-A to USB-A ‘Easy Transfer’ cable with a network adapter in the middle.
Alternatively, there is ‘Target Disk Mode’, which turns the machine into, basically, an external hard disk. Which works great for troubleshooting Macs that won’t boot due to software issues, or to get info off a machine without really turning it on (at least without booting to OS). This would have to be implemented on a mainboard firmware level.
Both these features already work through USB-C on Macs, so it stands to reason they should be very possible on a Windows machine as well. USB-C is up for the task, now we just need Windows to catch up!