Personally, I feel Tesla will be using this in the destination program to install 2-4 HPWCs wired to 1-2 100 amp circuits and banking that "most" of the time, a 48 amp max car will be plugging in. Couple that with SOC differences, and the chances that either vehicle is artificially limited are lessened. At scale, this is much cheaper overall and helps either Tesla (if paying installation) or the business hosting the destination chargers (if they are paying for it). Either way, I think it will be quite popular.
SOC difference will make _no difference_ for HPWC charging. At most you could hope for the other car is done charging and just parked there, otherwise you will get fractional charging. 20@200V? Could happen, could be common.
Sort of a side note, IMHO Tesla should have a software update to recognize HPWC's and unlock the charging handle when charging is complete, even if the car is locked.