I imagine they wouldn't remove the ability to charge over USB-C, but simply add a new MagSafe port. This would effectively free up an extra port when traveling, and you could still use USB-C charging from hubs, monitors, or third-party chargers.
This sounds very plausible. I have a Dell Windows laptop with an ordinary barrel charger port which can also be kept charged by a dock plugged into the USB C port. It seems a good arrangement. I haven't tried charging the laptop from a USB C wall wart rather than a dock, but it seems plausible it would work and it could be a handy feature if you forgot the charger somewhere.
