Just in case anyone is thinking of buying a Panasonic Lumix S1 Pro for the purpose of being able to record 10 bit 4:2:2, don't!
I spoke to Panasonic today, Friday 15th March, and they tell me that the upgrade required to unlock this is not yet available and there is no date set for when it will be available.
They thanked me for my observation and query but be aware there is no website out there selling the camera, that I can see at the moment, informing you it cannot be done.