At 8 cents for power and rent wouldn't it continue to net a measly amount of BTC even if price dropped to about 16000?
Edit - assuming 100TH/s, 3010 watts.
I included
capital cost in that calculation with straight-line depreciation, assuming the average Whatsminer M30S or Antminer S19 will last for 4 years. That is why production cost per coin is higher than power cost.