ASIC space heaters?
If you think that miners can find a profitable use for the waste heat from the mining process then that would allow them to use even
more power than the estimates given.
Yes, but it wouldn't be wasted. Say resistor wire with built-in mining hardware costs about the same as regular resistor wire and that 6% of electricity production goes to heating. Then all those 6% (instead of 3%) would be used for mining. No other mining would take place as it would be highly unprofitable. More power would be used for mining but used efficiently and at no cost to society.