Alex plugged the PIC into a breadboard with an LED and resistor. Applied 5V. The LED blinked! Windows 10 had been conquered.
This method replaces the problematic Prolific driver with a version that Windows 10 still accepts.
The uses libusb but has signed drivers from Microchip. It works out of the box on Windows 10 with MPLAB X IDE. If you program PICs more than once a month, upgrade.