Where did I indicate a timescale (outside of "it took us a while" -- wherein I said that progress is slow)? As many others have pointed out, energy efficiency is seen as a bug and bitcoin has repeatedly increased hashing difficulty in order to offset increasing efficiency. Likewise, if a locale is known to have cheap power, miners move in until the power isn't cheap anymore. Eventually we'll be on 90+% renewables, and it won't be as bad, but ultimately, bitcoin is a space heater, and never a battery unless you devise a system to capture, store, and generate electricity from that heat.

It will not. Bitcoin is literally designed specifically to make sure this never happens.

Again, as soon as you manage to develop a way to mine bitcoin more efficiently, the difficulty of mining will automatically go up to make sure you are still wasting just as much energy.